Document:

<PAGE>   1
                                                                   Exhibit 10.16

                            FIRST AMENDMENT TO LEASE

     THIS FIRST AMENDMENT TO LEASE, made and entered into as of the 23rd day of
February, 2001 by and between Missouri Falls Partners, an Arizona Partnership,
hereinafter referred to as "Landlord", and CSK AUTO, Inc., an Arizona
Corporation as "Tenant".

                                   WITNESSETH

     WHEREAS, Landlord leased certain premises to Tenant, known as Suite 100
consisting of approximately 3,351 Rentable Square Feet in the Missouri Falls
Building, at 645 E. Missouri Ave., in the City of Phoenix, County of Maricopa,
State of Arizona, pursuant to that certain lease dated the 20th day of April,
2000; the premises being more particularly described therein; and

     WHEREAS, Landlord wished to lease additional premises to Tenant and Tenant
wishes to lease additional premises from Landlord; and

     WHEREAS, Landlord and Tenant wish to amend said Lease,

     NOW THEREFORE, in consideration of these presents and the mutual covenants
contained hereinafter, and for such other good and valuable consideration the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant
hereto agree that said Lease shall be and the same is hereby amended as follows:

     1.   Paragraph 1 "Leased Premises" is hereby amended by the replacement of
          Exhibit A with a new Exhibit A-1 attached hereto and made a part
          hereof, showing the expanded area of approximately 480 rentable square
          feet and the existing area of approximately 3,351 rentable square
          feet, for a new total of leased space of approximately 3,831 rentable
          square feet.

     2.   The term of the expansion shall commence April 1, 2001 and shall
          terminate October 31, 2006, which date shall be coterminous with the
          original lease.

     3.   In Subparagraph 3 of Paragraph 5 "Rental, Definitions", the "Base
          Operating Costs" for the expansion area shall be considered as the
          operating costs for the year 2001.

     4.   Tenant's proportionate share for the expansion area shall be deemed to
          be Twenty-Six one Hundreths percent (0.26%)

     5.   In Paragraph 1 of the Addendum to Lease "Rental Schedule", the amount
          of Four Thousand Eight Hundred Eighty Six and 88/100 ($4,886.88)
          Dollars shall be deleted and a new rental schedule shall be inserted
          as follows:

          May 1, 2001 - October 31, 2001
          $17.50 PSF or $5,586.88 per month plus applicable taxes

          November 1, 2001 through October 31, 2006

          From November, 1, 2001 through the end of the lease term, Base Rent
          per square foot for the Demised Premises shall be adjusted to an
          amount equal to the Base Rent in effect on October 31, 2001 multiplied
          by the lesser of (I) 115%, and (ii) the Cumulative CPI Factor for the
          period from November 1, 1996 through October 31, 2001. There shall be
          no decrease in the Base Rent as a result of the adjustment
          contemplated by this paragraph of the Addendum.

          As used herein "Cumulative CPI Factor" shall mean a fraction, the
          numerator of which is the Current Number and the denominator of which
          is the Base Number. As used in this definition, the following
          capitalized terms shall mean: "Base Number" shall mean the Consumer
          Price Index for All Urban Consumers, United States City Average, All
          Items (1982-84=100), issued by the Bureau of Labor Statistics of the
          United States Department of Labor (hereinafter called the "Index") for
          the month immediately prior to the period in question; and "Current
          Number" shall mean the latest Index published for the last month of
          the period in question by the Bureau of Labor Statistics or other
          governmental agency then publishing the Index (or if the Index is no

<PAGE>   2
     longer published, the index of consumer prices reasonably deemed by
     Landlord to be comparable to the Index), after making such adjustments as
     may be prescribed by the agency publishing the same or as otherwise so
     deemed to be required to compensate for changes subsequent to January 1,
     1984 in the base, items included or method of compilation thereof.

6.   Tenant shall receive one (1) additional unreserved parking space.

7.   Tenant accepts space in an "As-is" condition.

8.   All other terms and conditions of the Lease as amended shall remain the
     same.

IN WITNESS WHEREOF, Landlord and Tenant have executed this instrument by proper
persons thereunto duly authorized so to do on the day and year first
hereinabove written.

CSK AUTO, INC.                          Missouri Falls Partners, an
An Arizona corporation                  Arizona partnership
                                        By: Insignia/ESG, a
                                        Delaware corporation as Agent

By:  /s/ Lon B. Novatt                  By:  /s/ [ILLEGIBLE]
   -----------------------------           --------------------------------
              (Name)

Its: Senior Vice President              Its:  Director
    ----------------------------            -------------------------------
             (Title)

<PAGE>   3

                                  [FLOORPLAN]

--------------
drawing:
  EXHIBIT A
--------------
job no:
  00089
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date:
  2/14/01
--------------

------------------------------
project:
  CSK AUTO
  MISSOURI FALLS

  625 EAST MISSOURI
  PHOENIX, AZ 84012
------------------------------

[VICTOR JOHN SPURLOCK AIA LOGO]

                 VICTOR JOHN SPURLOCK AIA
-----------------------------------------
                    2622 East Acoma Drive
              Phoenix, Arizona 85032-4831
602.482.3737 (voice) - 602.482.3797 (fax)
<PAGE>   4
                                                           [INSIGNIA ESG LOGO]

                               BASE YEAR LEASE

DATE: APRIL 20, 2000
      -------------------------

LANDLORD: Missouri Falls Partners, an Arizona Partnership
          ---------------------------------------------------------------------

TENANT:   CSK Auto, Inc., an Arizona Corporation
       ------------------------------------------------------------------------

I.        LEASED PREMISES
          The leased premises (the "Leased Premises") are as shown on Exhibit
          "A" attached hereto are further defined as:

          Suite 100 on the 1st floor of the Missouri Falls Building located at
          ---------------------------------------------------------------------
          645 E. Missouri Avenue, Phoenix, AZ 85012 and consisting of
          ---------------------------------------------------------------------
          approximately 3,351 Rentable Square Feet.
          ---------------------------------------------------------------------

          SQUARE FOOTAGE

          Even though the Base Rent and other charges (the "Rent") set forth in
this Lease is or may be calculated on a per square foot basis, the parties
specifically acknowledged and agree that the amount of Rent which the Tenant is
obligated to pay is for the space which it is leasing, regardless of the actual
size of that space. (The Tenant acknowledged the Landlord's use of a load factor
in the calculation of the square footage.) Therefore, if it is found that the
actual square footage of the Demised Premises is more or less than the
approximate square footage set forth in this Lease Agreement, the parties
specifically understand and agree that the amount of Rent to be paid by the
Tenant on a monthly basis shall not be adjusted either upward or downward.
Furthermore, the Tenant's proportionate share, as defined in Article V, Section
3, shall not be adjusted either upward or downward if it is found that the
Demised Premises contain more or less than the approximate square footage set
forth in this Lease.

II.       LEASE
          The Landlord hereby leases to the Tenant, and the Tenant hereby
leases from the Landlord, the Leased Premises, upon the terms and conditions
set forth in this Lease (the "Lease").

III.      TERM
          This Lease is for a term of seventy-seven (77) months commencing June
1, 2000 (the "Commencement Date") and terminating October 31, 2006, (The
"Termination Date").
          If the Leased Premises or the Building in which the Leased premises
are located are not completed at the Commencement Date and possession of the
Leased Premises is not delivered to Tenant by the Commencement Date, the
Commencement Date shall be the first day of the calendar month following the
delivery of the Leased Premises to Tenant. If the Leased Premises are delivered
to Tenant and Tenant accepts possession on any day earlier than the
Commencement Date, the rental for the interim shall be paid by Tenant on a
prorata basis, but such earlier taking of possession shall not change the
Termination Date of this Lease.

V.        RENTAL, DEFINITIONS
          Tenant agrees to pay as base rental Four thousand eight hundred eighty
six dollars and eighty eight one hundredths ($4,886.88) per month (the "Base
Rent") for each and every month of the Lease (plus any excise, privilege or
sales taxes levied on the rentals or the receipt thereof, except Landlord's
income tax), payable in advance, without offset or deduction, on the first day
of each month commencing with the Commencement Date of the Lease.
          The Base Rent shall be subject to adjustment each calendar year to
compensate for increases in Landlord's "Operating Costs" (as hereinafter
defined). However, in no event, shall Tenant's Base Rent be less than the Base
Rent specified herein.
          Landlord's "Base Operating Cost" shall be the Operating Costs for the
calendar year, during which the Commencement Date occurs.
          "Operating Costs" shall be determined on an accrual basis for each
calendar year by taking into account, on a consistent basis, all costs of
management, maintenance, and operation of the Building, including but not
limited to the costs of cleaning, utilities, air conditioning and heating,
plumbing, elevator, insurance, ground rent, landscaping costs and the cost of
improvements installed to reduce the above-listed operating costs together with
interest at the Prime Rate (as hereinafter defined) on the unamortized portion
of such cost, amortized over such reasonable period as Landlord shall determine,
and all other costs which can properly be considered operating expenses incurred
in the management, maintenance and operation of the Building.
          The Operating Costs shall be determined for each calendar year. If the
Operating Costs for any calendar year exceed the Base Operating Cost, Tenant's
rent for said calendar year shall be increased by an amount equal to Tenant's
"Proportionate Share" (as hereinafter defined) of such excess which increased
rental for such calendar year Tenant agrees to pay to Landlord in accordance
with the statements rendered.
          Each calendar year Landlord may elect to require that the rental be
adjusted for that year effective January 1 on the basis of Landlord's estimates
of increases or decreases in Operating Costs, which adjusted rental Tenant
agrees to pay in accordance with the statements rendered. A final adjustment of
the rental for each calendar year shall be made the following year based upon
the final Operating Costs, determined as herein provided and examined by
Landlord's regularly employed accountants. Appropriate fair adjustments shall be
made for costs which vary with occupancy and where tenants pay costs that in
other leases are paid by Landlord. In no event, however, shall Tenant's rent be
less than the Base Rent specified above.

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     Tenant hereby agrees to pay, as additional rent, Tenant's Proportionate
Share of any Real and Personal Property taxes (as hereinafter defined) assessed
or levied for any tax year (the "Tax Year") or portion thereof occurring during
the term of this Lease in excess of the base taxes. If the Real and Personal
Property taxes for any Tax Year are lower than the Base Taxes, Tenant shall not
be entitled to any refund whatsoever.

     After landlord has received the tax bill(s) for each Tax Year, Landlord
shall furnish Tenant with a written statement of the amount due as Tenant's
Proportionate Share of Real and Personal Property taxes in excess of the Base
Year Taxes, and within thirty (30) days of the date of such statement, Tenant
shall pay the amount due in one lump sum. Alternatively, Landlord shall have the
right to estimate Tenant's Proportionate Share of Real and Personal Property
taxes in excess of the Base Year Taxes, which sums Tenant agrees to pay in
accordance with the statements rendered, in which event a final annual
adjustment shall be made based upon the Real and Personal Property taxes
actually assessed or levied. The failure of Landlord to send Tenant any such
statement shall not constitute a waiver by Landlord of its right to require
Tenant to pay its Proportionate Share of such excess. Any fractional Tax Year in
the first or final year of the Lease term shall be treated proportionately on a
three hundred sixty (360) day year basis.

     For the purposes of this Lease, Rental, Definitions, the following terms
shall have the following meanings:

     1.  "Tax Year" shall mean the twelve (12) month period employed for real
and personal property taxation purposes by each of the taxing authorities in the
State of Arizona.

     2.  "Real and Personal Property Taxes" shall mean and include a) all real
property taxes and personal property taxes, charges and general and special
assessments which are levied or assessed upon or with respect to the Building
and any improvements, fixtures, and equipment and all other personal property of
Landlord located on, in or about the Building and/or used in connection with the
operation thereof and b) all taxes which shall be levied or assessed in addition
to or in lieu of such real or personal property taxes, but shall not include any
net income, franchise, capital stock, estate or inheritance taxes.

     3.  Tenant's "Proportionate Share" shall mean the ratio, expressed as a
percentage, of the rentable area of the Leased Premises to the rentable area of
the Building, which the parties hereby stipulate to be One and seventy-nine one
hundredths percent (1.79%).

     4.  As used in this Lease, the term "Building" includes the building and/or
buildings and adjoining parking areas, if any, and the land and/or air space
which is the site and grounds for such buildings and parking areas, regardless
of the name under which such buildings may be known.

 5.  As used in this Lease, the term "Prime Rate" shall mean the sum of (a)
that rate of interest, charged by the Bank One, a national banking association
(or any successor to the business of such bank), and announced by such bank,
from time to time, as its "prime rate", and (b) two (2) percentage points above
the annual rate of interest specified in clause "(a)" immediately hereinabove.

     6.  "Base Taxes" shall be the Real and Personal Property taxes assessed or
levied for the calendar year in which the Commencement Date occurs.

VII.  INITIAL CONSTRUCTION -- See Addendum

VIII. REPAIRS AND ALTERATIONS

     Landlord agrees to make all necessary repairs to the exterior walls,
exterior doors, windows and corridors of the Building. Landlord agrees to keep
the Building in a clean, neat and attractive condition. Landlord agrees to keep
all building standard equipment such as elevators, plumbing, heating, air
conditioning and similar equipment in good repair, but Landlord shall not be
liable or responsible for breakdowns or temporary interruptions in service when
reasonable efforts are used to restore service.

     Tenant agrees that it will pay for the cost of all repairs to the Leased
Premises not required above to be made by Landlord and be responsible for all
redecorating, remodeling, alteration and painting required by it during the term
of this Lease. Tenant shall pay for any repairs to the Leased Premises, or the
Building, made necessary by any negligence or carelessness of Tenant, its
employees contractors or invitees. Tenant agrees to maintain the Leased Premises
in a clean, neat and sanitary condition.

     Tenant may place partitions and fixtures and make improvements and other
alterations to the interior of the Leased Premises at Tenant's expense,
provided, however, that prior to commencing any such work Tenant shall first
obtain the written consent of Landlord to the proposed work and Landlord shall
have the right to review and approve all plans. Landlord may require that said
work be done by Landlord's own employees or under Landlord's direction but at
the expense of Tenant, and Landlord may, as a condition to consenting to such
work, require that Tenant give security that the Leased Premises will be
completed free and clear of liens and in a manner satisfactory to Landlord.
Notwithstanding the foregoing, any such improvements or alterations by Tenant
shall conform to and be in substantial accordance in quality and appearance with
the quality and appearance of the improvements in the remainder of the Building.
Any such improvements shall become the property of Landlord upon expiration of
this Lease or sooner termination or this lease. Tenant shall remove any movable
furniture and equipment upon termination of this Lease and shall deliver the
Leased Premises to Landlord in as good condition as received, broom clean,
normal wear and tear excepted. In the event Tenant receives consent of the
Landlord and uses Tenant's own contractor for any such improvements than Tenant
must provide Landlord with contractor's evidence of workmen's

                                       2

<PAGE>   6
compensation and liability insurance in amounts sufficient to Landlord and have
acquired the necessary building permits to prior to commencing any such
construction.

IX.  FIRE OR CASUALTY INSURANCE

     In the event that the Leased Premises are wholly or partially destroyed by
fire or other casualty covered by the usual form of fire and extended coverage
insurance rendering them untenantable, Landlord shall, to the extent of
insurance proceeds actually received by Landlord, rebuild, repair or restore the
Leased Premises to substantially the same condition as when the same were
furnished to Tenant and this Lease shall remain in effect during such period. In
the event of total destruction, rent shall abate during the period of
reconstruction, and in the event of partial destruction, rent shall abate
prorata during the period of reconstruction. In the event, however, that the
building containing the Leased Premises is damaged or destroyed to the extent of
more than one-third (1/3) of its replacement cost, Landlord may elect to
terminate this Lease.

     Tenant shall be responsible for and shall provide Tenant's own insurance
coverage, and supply Landlord with evidence of such coverage with respect to any
furniture, fixtures, improvements, betterments, equipment, and personal property
belonging to Tenant and placed by Tenant in or upon the Leased Premises. Tenant
agrees and warrants to Landlord that any fire insurance policy, extended
coverage policy, casualty and loss policy, or other policy or policies carried
by Tenant in connection with this Lease or the Leased Premises and/or insuring
Tenant's property or effects located in or upon the Leased Premises shall each
contain a provision whereby the insurance carrier waives any right of
subrogation against the Landlord.

     Provided Landlord can obtain such waiver of subrogation rights with regard
to policies of fire or casualty insurance obtained by Landlord with regard to
the Building, Landlord hereby releases and waives any and all rights of
subrogation against Tenant which, in the absence of this release and waiver,
would arise in favor of any insurance company insuring Landlord against loss of
fire, extended coverage casualty and loss of any other type, resulting from
damage to or destruction of the building of which the Leased Premises form a
part or any portion thereof or in damage to or destruction of the property of
Landlord in the Building. Landlord shall not be required to obtain such
insurance policies except through insurance companies satisfactory to the
Landlord and the holder of any mortgage covering the Leased Premises.

X.   USE OF LEASED PREMISES

     The Leased Premises are leased to Tenant for the sole purpose of General
offices and for no other purpose whatsoever. Tenant agrees that it will use the
Leased Premises in such manner as to not interfere with or infringe upon the
rights of other tenants in the Building. Tenant agrees to comply with all
applicable laws, ordinances and regulations ("Laws") in connection with its use
of and/or transfer of any interest in the Leased Premises and in performing all
repairs, remodeling and alterations to the Leased Premises, including all
Environmental Laws and obtaining all necessary permits, licenses or other
authorizations required pursuant to such Laws. Tenant shall supply all
documentation regarding compliance with the Laws, including written
documentation by the appropriate governmental authority that all such Laws have
been complied with.

XI.  SIGNS

     Landlord shall retain absolute control over the exterior appearance of the
Building and the exterior appearance of the Leased Premises as viewed from the
public halls. Tenant will not install, or permit to be installed, any drapes,
shutters, signs, lettering, advertising, or any items that will in any way alter
the exterior appearance of the Building or the exterior appearance of the Leased
Premises as viewed from the public halls or exterior of the Building.

XII. CONFIDENCE REPOSED IN TENANT AND TENANT'S REPRESENTATIONS AND WARRANTIES

     It is agreed that one of the conditions moving Landlord to make this Lease
is the personal confidence reposed by it in Tenant, combined with the belief
that Tenant will be a tenant and occupant satisfactory to Landlord and the other
occupants of the Building. Should Tenant vacate or abandon the Leased Premises
during the term hereof, Landlord, at Landlord's discretion, shall have the right
to cancel this Lease without obligation to Tenant.

     Tenant represents and warrants as follows:

     A.   Tenant has never been in violation of or investigated for violation
of any Environmental Laws.

     B.   Tenant will not engage in any activity involving Hazardous Substances
or which could create an Environmental Condition on the Leased Premises or
permit any third party to do so, without Landlord's written consent.

     C.   Tenant will immediately notify Landlord of (i) any investigation,
proceeding, notice or claim regarding a violation of any Environmental Law
relating to the Leased Premises or other premises which Tenant occupies, an
Environmental Condition on the Leased Premises, or a Release of Hazardous
Substances on the Leased Premises, (ii) any submissions or notifications made by
Tenant to governmental authorities or others concerning Environmental Conditions
or Hazardous Substances on the Leased Premises, and (iii) the existence of any
Hazardous Substances or Environmental Conditions on or about the Leased Premises
or on property adjoining or in the vicinity of the Leased Premises that may be
in violation of an Environmental Law (regardless of whether Tenant is
responsible for its existence). Tenant will take all appropriate response
actions in the event of an occurrence of an Environmental Condition on the
Leased Premises and shall resolve all environmental problems to the satisfaction
of Landlord. In the event of any investigation, notice of violation or other
action taken by a governmental agency or private person relating in any way to
Tenant's operation on the Leased Premises, Tenant shall be solely responsible
for complying with all legal requirements, including cleanup of the Leased
Premises, and requirements imposed by the governmental authority. Tenant shall
not, however take any remedial action in response to the presence of any
Hazardous Substance or Environmental Condition, nor enter into any settlement
agreement, consent decree or other compromise without first notifying Landlord
and affording Landlord ample opportunity to appear, intervene, or otherwise
appropriately assert and protect Landlord's interests.

     D.   Tenant's will provide Landlord with an environmental audit at the end
of each Lease year, detailing the use, management and disposal of any Hazardous
Substances on the Leased Premises with the Environmental Laws.

     As used in this Lease, the following terms shall have the meanings
specified below:

     E.   "Environmental Law(s)" shall mean any federal, state or local law,
including statutes, ordinances, rules, common law and guidelines, now in effect
or hereinafter enacted, pertaining to health, industrial hygiene, or the
environment, including without limitation, the Comprehensive Environmental
Response, Compensation and Liability Act, the Resource Conservation and Recovery
Act, the Toxic Substances Control Act, the Superfund Amendments and
Reauthorization Act, the Clean Air Act, the Federal Water Pollution Control Act,
the Safe Drinking Water Act, and the Solid Waste Disposal Act.

     F.   "Hazardous Substances" shall mean any material, waste, or substance
which may or could pose risk of injury or threat to health or the environment
and any substance that is or becomes regulated by any federal, state or local
law.

     G.   "Environmental Condition" shall mean any condition with respect to
soil, air, surface or groundwater which could require remedial action and/or may
result in claims, demands, and/or liabilities by or to third parties, including
without limitation, governmental entities.

     H.   "Release" shall mean releasing, spilling, leaking, pumping, pouring,
emitting, emptying, discharging, injecting, escaping, leaching, disposing or
dumping.

     Tenant's failure to perform or observe any of the above representations and
warranties shall constitute a substantial breach of the Lease and shall entitle
Landlord to pursue any and all remedies allowed by law or at equity, including
without limitation canceling and terminating the Lease and imposing a rent
surcharge.

                                       3

<PAGE>   7
XIII.     ASSIGNMENT AND SUBLETTING

     A.   Tenant for itself, its heirs, distributees, successors and assigns,
expressly covenants that it shall not, by operation of law or otherwise, assign,
sublet, mortgage or encumber all or any part of this Lease or the Leased
Premises, including environmental liens in favor of a governmental entity, or
permit the Leased Premises to be used by others without the prior written
consent of Landlord in each instance. Any attempt to do so by the Tenant shall
be void. The consent by Landlord to any assignment, sublet, mortgage or
encumbrance or use of all or any part of the Leased premises by others, shall
not constitute a waiver of Landlord's right to withhold its consent to any other
assignment, sublet, mortgage, or encumbrance or use of all or any part of the
Leased Premises by others. Without the prior written consent of Landlord, this
Lease and the interest of Tenant therein or any assignee of Tenant therein,
shall not pass by operation of law, and shall not be subject to garnishment or
sale under execution in any lawsuit or proceeding which may be brought against
or by Tenant or any sublessee or assignee of Tenant.

     B.   If Tenant requests Landlord's consent to an assignment of this Lease
or subletting of all or any part of the Leased Premises, Tenant shall submit to
Landlord: (1) the name of the proposed assignee or subtenant, (2) the terms of
the proposed assignment or subletting, (3) the nature of the proposed
subtenant's or assignee's business; and (4) such information as to such
subtenant's or assignee's financial responsibility and general reputation as
Landlord may require.

     C.   Upon the receipt of the request pursuant to Paragraph XIII(B)
hereinabove and information from Tenant, Landlord shall have the option, at
Landlord's discretion, to be exercised in writing within thirty (30) days after
such receipt, to either (1) cancel and terminate this Lease, if the request is
to assign or sublet all of the Lease and/or the Leased Premises or, if the
request is to sublet or assign a portion of the Lease and/or the Leased
Premises, to cancel and terminate this Lease with respect to such portion, in
each case as of the date set forth in Landlord's notice of exercise of such
option; (2) to grant said request, or (3) deny said request if Landlord finds
such subtenant or assignee unacceptable.

     D.   In the event Landlord shall elect to cancel and terminate this Lease,
Tenant shall surrender possession of the Leased Premises, or the portion of the
Leased Premises which is the subject of the request, as the case may be, on the
date set forth in such notice in accordance with the provisions of this Lease
relating to surrender of the Leased Premises. If the lease shall be canceled as
to a portion of the Leased Premises only, the rent and other charges payable by
Tenant hereunder shall be reduced proportionately according to the ratio that
the number of square feet in the portion of space surrendered bears to the
square feet of space at the initial Leased Premises.

     E.   In the event that Landlord shall consent to a sublease or assignment
pursuant to the request from Tenant, Tenant shall cause to be executed by its
assignee or subtenant an agreement satisfactory to Landlord, whereby such
assignee or subtenant agrees to perform faithfully and to assume and be bound by
all of the terms, covenants, provisions and agreements of this Lease for the
period covered by the assignment or sublease and to the extent of the space
sublet or assigned. In addition, Tenant agrees that with regard to each such
sublease or assignment so consented to by Landlord, Tenant: (1) will not collect
more than one month's rent in advance, (2) will not terminate or cancel such
sublease or assignment without Landlord's prior written consent, (3) will be
responsible for all the acts and omissions of said sublessees or assignees, (4)
will only sublease at the rental which Tenant is then paying to Landlord, (5)
shall pay to Landlord promptly, following receipt of the amount of the value of
any consideration received by Tenant from any assignment of this lease, (7)
Tenant shall not assign or sublet the premises to another existing tenant in the
building housing the Leased Premises, and (8) An executed copy of each sublease
or assignment and assumption of performance by the sublessee or assignee, on
Landlord's standard form, shall be delivered to Landlord within five (5) days
prior to the commencement of occupancy set forth in such assignment or sublease.
No such assignment or sublease shall be binding on Landlord until Landlord shall
have actually received such copies as required herein.

     F.   In no event shall any assignment or subletting to which Landlord may
consent, release or relieve Tenant from its obligations to fully perform all of
the terms, covenants and conditions of this Lease on its part to be performed.

     G.   In the event this Lease is canceled at Landlord's option as provided
hereinabove, neither of the parties shall have any further obligations
hereunder, except as may be expressly provided herein and except Tenant shall
pay all rents, charges and all other amounts due, as set out in the Lease, to
the date Tenant is notified of such cancellation.

XIV.      EMINENT DOMAIN

     In the event any portion of the Leased Premises is taken from Tenant under
eminent domain proceedings, Tenant shall have no right, title or interest in any
award made for such taking.

XV.       WAIVER AND SEVERABILITY

     The consent of the Landlord in any instance to any variation of the terms
of the Lease, or the receipt of rent with knowledge of any breach, shall not be
deemed to be a waiver as to any breach of any covenant or condition herein
contained, nor shall any waiver be claimed as to any provisions of this Lease
unless the same be in writing, signed by Landlord. This Lease and any written
amendment, exhibits or addenda hereto contain the entire agreement between the
parties. If any term or provision of this Lease or any application thereof shall
be invalid or unenforceable, then the remaining terms and provisions of this
lease and any other application of such term or provision shall not be affected
thereby.

XVI.      USE OF COMMON FACILITIES

     All elevators, stairways, halls and areas for the common use of all tenants
at the Building shall be open to reasonable use by Tenant, its customers,
clients and employees. Tenant and its officers, agents and employees agrees to
park their motor vehicles only in areas designated from time to time for that
purpose or otherwise as permitted in writing by Landlord.

XVII.     SERVICES

     A.   Landlord agrees to provide air conditioning, heat, water and
electricity for lighting and normal office usage during the customary business
hours of the Building as established by Landlord, and to provide janitor
services of the type customarily furnished by comparable buildings, which shall
consist essentially of a nightly clean-up five (5) days per week, the costs of
which shall be includable in Operating Costs hereunder.

     B.   Tenant agrees to pay for all utilities and other services and expenses
used or incurred by Landlord on Tenant's behalf not specifically provided for
above.

XVIII.    ENTRY OF LANDLORD

     Landlord reserves the right, without abatement of rent and other charges
due hereunder from Tenant to enter upon or have its agent enter the Leased
Premises at reasonable times for the inspection of the same, including
environmental assessments and audits, to make necessary repairs, including any
actions necessary to remediate, abate or cleanup any Hazardous Substances or
Environmental Conditions on the Leased Premises, the cost of which Tenant will
be responsible pursuant to paragraph XXVI below, to post notices of
non-responsibility and Landlord reserves the right, during the last six (6)
months of the term of this Lease to show the Leased Premises, at reasonable
times, to prospective purchasers or tenants.

     Tenant hereby waives any claim for damages for any injury or inconvenience
to or interference with Tenant's business, any loss of occupancy or quiet
enjoyment of the Leased Premises, and any other loss occasioned by Landlord's
entry. Landlord shall at all times have and retain a key with which to unlock
all of the doors in, upon and about the Leased Premises, excluding Tenant's
vaults and safes (as the same are permitted by Landlord to be upon the Leased
premises), and Landlord shall have the right to use any and all means which
Landlord may deem proper to open said doors in an emergency in order to obtain
entry to

                                       4
<PAGE>   8
the Leased Premises and any entry into the Leased Premises obtained by Landlord
by any of said means, or otherwise, shall not under any circumstances be
construed or deemed to be a forcible or unlawful entry into, or a detainer of,
the Leased Premises or an eviction of Tenant from the Leased Premises or any
portion thereof.

XX.       SUBORDINATION AND ATTORNMENT
          Landlord reserves the right to place liens and encumbrances on the
Leased Premises superior in lien and effect to this Lease. This Lease and any
and all renewals, modifications, replacements or extensions thereof, at the
option of the Landlord, shall be subject and subordinate to any liens and
encumbrances now or hereinafter imposed by Landlord upon the Leased Premises or
the Building and Tenant agrees to execute and deliver upon demand (and to cause
all sublessees and assignees under Tenant to execute and deliver upon demand)
such instruments subordinating this Lease (and all subleases and assignments
pursuant to this Lease) to any such lien or encumbrance as shall be required by
Landlord.
          In the event Landlord's interest in the Leased Premises is derived
from another party and said Lease should be terminated by the other party,
Tenant agrees to attorn (and to cause all sublessees and assignees under Tenant
to so attorn) to the other party, its successors and assigns as Landlord on this
Lease.
          In the event any proceedings are brought for the foreclosure of any
mortgage on the Leased Premises, Tenant will attorn (and Tenant will cause all
sublessees and assignees under Tenant to so attorn) to the purchaser at
foreclosure sale and recognize the purchaser as the Landlord under this Lease.
The purchases by virtue of such foreclosure shall be deemed to have assumed, as
substitute Landlord, the terms and conditions of this Lease until the resale or
other disposition of its interest by such purchaser. Such assumption, however,
shall not be deemed of itself an acknowledgment by the purchaser of the validity
of any then existing claims of Tenant (or the claims of any sublessees or
assignees under Tenant) against the prior Landlord.
          Tenant agrees to execute and deliver (and to cause all sublessees and
assignees under Tenant to execute and deliver) such further assurance and other
documents (including but not limited to a new lease upon the same terms and
conditions as this lease) confirming the foregoing as such purchaser may
reasonably request. Tenant on behalf of itself and on behalf of all sublessees
and assignees under Tenant waives any right of election to terminate this Lease
because of any such foreclosure proceedings. Tenant hereby irrevocably
constitutes and appoints Landlord as Tenant's attorney-in-fact to execute (and
to deliver to any third party) any documents hereinabove required to be executed
by Tenant, for and on behalf of Tenant, if Tenant shall have failed to do so
within ten (10) days after the request therefor by Landlord.

XXI.      NOTICES
          Any notices or demands to be given hereunder shall be in writing and
shall be given to Landlord and to Landlord's managing agent with regard to the
Building, at their respective offices and to Tenant at the Leased Premises, or
at such other address as either party shall designate, and shall be by
registered or certified United States mail, postage prepaid or, at the election
of Landlord, hand delivered.

XXII.     DEFAULT

          In the event Tenant fails to pay any rental due hereunder or fails to
keep and perform any of the other terms or conditions hereof, time being of the
essence, then five (5) days after written notice of default given to Tenant from
Landlord, the Landlord may, if such default has not been corrected, resort to
any and all legal remedies or combination of remedies which Landlord may desire
to assert including but not limited to one or more of the following: (1) lock
the doors to the Leased Premises and exclude Tenant therefrom, (2) retain or
take possession of any property on the Leased Premises pursuant to Landlord's
statutory lien, (3) enter the Leased Premises and remove all persons and
property therefrom, (4) declare this Lease at an end and terminated, (5) sue for
the rent due and to become due under this Lease, and for any damages sustained
by Landlord, (6) collect, directly from any sublessee or assignee under Tenant
all subrents and other charges payable by such sublessees or assignees, Tenant
hereby assigning to Landlord such subrents and other charges in the event of a
default by Tenant under this lease, and (7) continue this Lease in effect and
relet the Leased Premises on such terms and conditions as Landlord may deem
advisable with Tenant remaining liable for the monthly rent plus the reasonable
cost of obtaining possession of the Leased Premises and of any repairs and
alterations necessary to prepare the Leased Premises for reletting, less the
rentals received from such reletting, if any. No action of Landlord shall be
construed as an election to terminate this Lease unless written notice of such
specific intention is given to Tenant. Tenant agrees to pay as additional rental
all attorneys' fees and other costs and expenses incurred by Landlord in
enforcing any of Tenant's obligations under this Lease whether or not legal
action is commenced or judgement obtained. Any amount due from Tenant to
Landlord under this Lease which is not paid when due shall bear interest at the
"Prime Rate" that is in effect on the date such amount is due, accruing from
such date until paid. Furthermore, that rate of interest paid by Tenant on any
such amount shall be adjusted as the "Prime Rate" is adjusted.

XXII.     LATE PAYMENTS
          Tenant hereby acknowledges that the late payment by Tenant to
Landlord of rent or any additional rent or other sums due hereunder will cause
Landlord to incur costs not contemplated in this Lease, the exact amount of
which will be extremely difficult and impracticable to ascertain. Such costs
include but are not limited to processing, administrative and accounting costs.

          Accordingly, if any installment of rent or any additional rent or any
other sum due from Tenant shall not be received by Landlord within five (5) days
after written notice of such delinquency, Tenant shall pay to Landlord a late
charge equal to three percent (3%) of such overdue amount. The parties hereby
agrees that such late charges represent a fair and reasonable estimate of the
costs Landlord will incur by reason of late payment by Tenant. Neither
assessment nor acceptance of such late charge by Landlord shall constitute a
waiver of Tenant's default with respect to such overdue amount, nor prevent
Landlord from exercising any of the other rights and remedies granted under the
Lease. Nothing contained in this paragraph shall be deemed to condone,
authorize, sanction or grant to Tenant an option for the late payment of rent,
and Tenant shall be deemed in default in the payment of its rent should the same
not be paid by the date on which it is due.

XXIV.     BUILDING RULES AND REGULATIONS
          Tenant agrees to abide by all rules and regulations ("currently in
the form attached hereto") of the Building imposed by Landlord. Such rules and
regulations are imposed for the cleanliness, good appearance, proper
maintenance, good order and reasonable use of the Leased Premises and the
Building, and as may be necessary for the proper enjoyment of the Building by
all Tenants and their clients, customers and employees. The rules and
regulations may be change from time to time upon ten (10) days notice to
Tenant. Breach of the rules and regulations of the Building shall not be
grounds for termination of the Lease.

                                       5
<PAGE>   9
XXXIV.    TIME OF THE ESSENCE
          Time is of the respecting Tenant's performance of Tenant's
obligations pursuant to and in accordance with this Lease.

XXXV.     BINDING EFFECT
          The covenants and conditions herein contained shall, subject to the
provisions restricting Tenant's assignment and subletting, apply to and bind
the heirs, executors, administrators, personal representatives, successors and
assigns of the parties hereto.

XXXVI.    RECORDATION
          Tenant shall not record this Lease or any short form memorandum
thereof, without the prior written consent of Landlord, which Landlord may
withhold in Landlord's sole, absolute and unfettered discretion.

XXXVII.   NAME OF BUILDING
          Tenant shall not use the name of the Building for any purpose other
than as an address of the business to be conducted by Tenant in the Leased
Premises.

XXXVIII.  GOVERNING LAW
          This Lease and all the terms and conditions thereof shall be governed
by the laws of the State of Arizona.

XXXIX.    DEFINED TERMS AND PARAGRAPH HEADINGS
          The words "Landlord" and "Tenant" as used herein shall include the
plural as well as the singular. Words used in masculine gender include the
feminine and neuter. If there is more than one Tenant, the obligations hereunder
imposed upon Tenant shall be joint and several. The paragraph headings and
titles to the paragraphs of this Lease are not a part of this Lease and shall
have no effect upon the construction or interpretation of any part thereof.

XXXX.     WAIVER OF TRIAL BY JURY; CONSENT TO JURISDICTION AND VENUE
          EACH PARTY HEREBY WAIVES TRIAL BY JURY IN THE EVENT OF ANY LEGAL
PROCEEDING BROUGHT BY THE OTHER IN CONNECTION WITH THIS LEASE. EACH PARTY SHALL
BRING ANY ACTION AGAINST THE OTHER IN CONNECTION WITH THIS LEASE IN A FEDERAL
OR STATE COURT LOCATED IN MARICOPA COUNTY, ARIZONA; EACH PARTY CONSENTS TO THE
JURISDICTION OF SUCH COURTS; AND, EACH PARTY WAIVES TO ANY RIGHT TO HAVE ANY
PROCEEDING TRANSFERRED FROM SUCH COURTS ON THE GROUNDS OF IMPROPER VENUE OR
INCONVENIENT FORUM.

TENANT:                                      LANDLORD:
CSK Auto, Inc., an Arizona corporation       Missouri Falls Partners, an Arizona
                                               partnership
                                             By: Insignia/ESG, Inc., a Delaware
                                             corporation as Agent
By:   /s/ Lon B. Novatt                      By:   /s/ Donald B. Mudd
      --------------------------                   -----------------------------
      Lon B. Novatt

Its:  Senior Vice President                  Its:  Director
      --------------------------                   -----------------------------

Date: 4/20/00                                Date: 4/26/00
      -------------------------                    -----------------------------

                                       7
<PAGE>   10
unless Tenant continues to breach the same after ten (10) days written notice by
Landlord. Landlord shall not be responsible to Tenant for nonperformance by any
tenant or occupant of the Building of any rules or regulations.

XXV.    LIENS
        Tenant shall keep the Landlord, Leased Premises and building harmless
from and against any liens and claims arising out of any work performed,
materials furnished or obligations incurred by Tenant, and shall indemnify and
hold Landlord harmless against the same, together with all costs of suit and
attorney's fees incurred by Landlord in connection therewith.

XXVI.   INDEMNIFICATION OF LANDLORD
        Landlord shall not be liable to Tenant, and Tenant hereby waives all
claims against Landlord for any injury (including death) or damage to any person
or property in or about the Leased Premises by or from any cause whatsoever and
Tenant shall indemnify and hold Landlord, its successors, officers and employees
harmless from any and all claims, costs, expenses or liability of any kind
(including without limitation a decrease in the value of the Leased Premises and
reasonable consultants' and attorneys' fees) arising directly or indirectly
from: (i) injury (including death) or damage to any person or property
whatsoever occurring on or about the Leased Premises, (ii) Hazardous Substances
or an Environmental Condition on or about the Leased Premises, or (iii)
violations or claims of violations by Tenant of an Environmental Law. This
indemnification obligation shall be in addition to any other obligations and
liabilities Tenant may have to Landlord at law or equity, and shall survive the
term of this Lease and shall not be subject to any other provisions of this
Lease that operate to limit Tenant's liability.
        Tenant shall obtain and keep in effect during the term of this Lease a
policy of comprehensive liability insurance, including public liability and
property damage, with a minimum combined single limit of liability of One
Million Dollars ($1,000,000.00). Said policy or policies shall name Landlord and
its agents as additional insureds and shall be issued by an insurance company,
licensed to do business in the State of Arizona, and acceptable to Landlord.
Said policy or policies shall additionally provide that the insurance shall not
be canceled or modified unless thirty (30) days prior written notice has been
given to Landlord. Tenant shall supply Landlord with a certificate of the
insurance which it has obtained prior to its occupation of the leased premises.
Landlord shall have the right to request Tenant to provide additional insurance
or other form of security satisfactory to Lender in the event that Tenant's
activities on the Leased Premises involve Hazardous Substances.

XXVII.  TAXES
        Tenant agrees to pay or cause to be paid, before delinquency, any and
all taxes levied or assessed and which become payable during the term hereof
upon all of Tenant's equipment, furniture, fixtures and other personal property
located in the Leased Premises.

XXVIII. HOLDING OVER
        Upon the expiration or earlier termination of this Lease, Tenant shall
immediately surrender the Leased Premises to Landlord; such Leased Premises to
be broom clean, in good condition and repair, ordinary wear and tear excepted.
Upon Tenant's written request and Landlord's approval, Tenant may become a
Tenant on a month to month basis if Tenant remains in the premises upon Lease
expiration. Tenant shall be responsible for all monetary obligations pursuant to
the Lease Agreement that existed for the month prior to such expiration, or
until Landlord shall adjust the monthly rent with thirty (30) days written
notice. If the Tenant or any sublessee or assignee under Tenant holds over after
the expiration or earlier termination of this Lease without Landlord's express
written consent, Tenant shall be in default hereunder and in addition to all of
the rights or remedies available to Landlord, Tenant shall be obligated to pay
to Landlord rent at a rate established by Landlord with regard to the Leased
Premises for the time during which Tenant retains possession, which payment
shall not constitute a waiver of any of Landlord's other rights or remedies
provided herein.

XXIX.   INSOLVENCY OR BANKRUPTCY
        Either (a) the appointment of a receiver to take possession of all or
substantially all of the assets of Tenant; or (b) an assignment by Tenant for
the benefit of creditors; or (c) any action taken or suffered by Tenant under
any insolvency, bankruptcy or reorganization act, shall constitute a default and
breach of this Lease by Tenant. Upon the happening of any such event, Landlord
shall have all the rights herein provided in the event of any such default or
breach, including without limitation the right, at Landlord's option, to
terminate this Lease and enter the Leased Premises and remove all persons and
property therefrom. In no event shall this Lease be assigned or assignable by
operation of law or by voluntary or involuntary bankruptcy proceedings or
otherwise and in no event shall this Lease or any rights or privileges hereunder
be an asset of Tenant under any bankruptcy, insolvency or reorganization
proceedings.

XXX.    SALE BY LANDLORD
        In the event of a sale or conveyance by Landlord of the Leased Premises,
the Building, or in the building in which the Leased Premises are situated, the
same shall operate to release landlord from any further liability upon any of
the covenants or conditions, express or implied, herein contained in favor of
Tenant and in such event Tenant agrees to look solely to the responsibility of
the successor in interest of Landlord in and to this Lease. This Lease shall not
be affected by any such sale, and Tenant agrees to attorn to the purchaser or
assignee upon Landlord's request. Tenant shall deliver to such purchaser an
offset statement and an estoppel certificate in such form as Landlord may
request, and, in the event Tenant fails to deliver said statement and
certificate within ten (10) days after demand by Landlord, Tenant hereby
constitutes and appoints Landlord as Tenant's attorney-in-fact to execute said
statement and certificate. Tenant's failure to deliver an estoppel certificate
to Landlord as required herein shall be conclusive evidence against Tenant that
this Lease, with any amendments identified by Landlord, is in full force and
effect, that there are no uncured defaults by Landlord, that no more than one
month's rental has been paid in advance and that Tenant has no claims or offset
against Landlord.

XXXI.   ATTORNEY'S FEES
        In the event of any action or proceeding brought by either party against
the other under this Lease, the prevailing party shall be entitled to recover
its attorney's fees and costs in such action or proceeding. In the event
Landlord intervenes in or becomes a party or is made a party to any action or
proceeding arising in connection with this Lease in order to protect its rights,
then Tenant shall pay to Landlord the fees of Landlord's attorneys therein as
fixed by the court.

XXXII.  SURRENDER OF PREMISES
        The voluntary or other surrender of this Lease by Tenant, or a mutual
cancellation thereof, shall not work a merger, and shall, at the option of
Landlord, terminate all or any existing subleases or subtenancies, or may, at
the option of Landlord, operate as an assignment to Landlord of any or all such
subleases or subtenancies. Tenant agrees that there shall be no value to the
leasehold upon termination or cancellation of the Lease under its terms.

XXXIII. LIMITATION OF LANDLORD'S LIABILITY
        Tenant covenants and agrees that any claims that Tenant may have now or
hereafter against Landlord shall be asserted solely against and satisfied only
out of Landlord's right, title and interest in the Building and not from any
other thing or asset of Landlord. In no event shall any officer, director,
employee, agent, shareholder, partner, member or beneficiary of Landlord be
personally liable for any of Landlord's obligations hereunder.

                                       6
<PAGE>   11
                                    ADDENDUM

This shall serve as an Addendum to that Lease dated April 20, 2000 by and
between Missouri Falls Partners, an Arizona partnership as Landlord, and CSK
Auto, Inc., an Arizona corporation, Tenant, for Suite 100 of the Missouri Falls
Building located at 645 East Missouri Ave, but the language contained herein
shall prevail if in conflict with any previous language.

     1.   RENTAL SCHEDULE
          The first month of the lease term the rent shall be free, thereafter
          it shall be as follows: July 1, 2000 thru October 31, 2001 $4,886.88
          per month ($17.50) per rentable square foot) plus applicable taxes

          November 1, 2000 through October 31, 2006
          From November 1, 2001 through the end of the lease term, Base Rent per
          square foot for the Demised Premises shall be adjusted to an amount
          equal to the Base Rent in effect on October 31, 2001 multiplied by the
          lesser of (i) 115%, and (ii) the Cumulative CPI Factor for the period
          from November 1, 1996 through October 31, 2001. There shall be no
          decrease in the Base Rent as a result of the adjustment contemplated
          by this paragraph of the Addendum.

          As used herein "Cumulative CPI Factor" shall mean a fraction, the
          numerator of which is the Current Number and the denominator of which
          is the Base Number. As used in this definition, the following
          capitalized terms shall mean: "Base Number" shall mean the Consumer
          Price Index for All Urban Consumers, United States City Average, All
          Items (1982-84=100), issued by the Bureau of Labor Statistics of the
          United States Department of Labor (hereinafter called the "Index") for
          the month immediately prior to the period in question; and "Current
          Number" shall mean the latest Index published for the last month of
          the period in question by the Bureau of Labor Statistics or other
          governmental agency then publishing the Index (or if the Index is no
          longer published, the index of consumer prices reasonably deemed by
          Landlord to be comparable to the Index), after making such adjustments
          as may be prescribed by the agency publishing the same or as otherwise
          so deemed to be required to compensate for changes subsequent to
          January 1, 1984 in the base, items included or method of compilation
          thereof.

     3.   PARKING
          In consideration for the making of this Lease, Landlord and Tenant do
          hereby mutually agree that Landlord shall provide Tenant with ten (10)
          covered unreserved parking spaces throughout the term of this lease.

     4.   CONSTRUCTION
          Landlord agrees to pay Tenant within sixty (60) days of the full
          execution of this Lease, a construction allowance in the amount of
          Five Dollars ($5.00) per rentable square foot or Sixteen Thousand
          Seven Hundred Fifty-Five and no/100 ($16,755.00) Dollars for
          improvements to the space.

          Landlord will perform or cause to be performed all necessary plans,
          and permits, for the demolition of the existing demising corridor
          walls, demolition of the glass partitions in the existing conference
          room, demolition of the existing hard ceiling, and the construction of
          the new demising corridor walls, as may be required for tenant's
          occupancy of the space.

CSK AUTO, INC.,                         Missouri Falls Partners, an
an Arizona corporation                  Arizona partnership
                                        By: Insignia/ESG a Delaware
                                        Corporation as Agent

By: /s/ Lon B. Novatt                   By: /s/ Donald B. Mudd
    -----------------------------           -------------------------------
    LON B. NOVATT                           DONALD B. MUDD

Its: Senior Vice President              Its: Director
    -----------------------------           -------------------------------

<PAGE>   12
                             RULES AND REGULATIONS

1.   PUBLIC AREA. All public areas of the Building shall be under the sole and
absolute control of Landlord and Landlord shall have the exclusive right to
regulate, modify and control these areas.

2.   WIRING. When electric wiring of any kind is introduced, it must be
connected as directed by the Landlord and no boring or cutting for wires will be
allowed except with the written consent of the Landlord. No apparatus, other
than normal office machines and equipment of any kind shall be connected with
the electric wiring of the Leased Premises and/or the Building without the
written consent of the Landlord.

3.   INCREASE IN RISK. No tenant shall do anything in the Leased Premises,
and/or the Building or bring or keep anything therein, which will in any way
increase or tend to increase the risk of fire, or which shall conflict with the
regulations of the Fire Department or the fire laws, or with any rules or
ordinances established by the Board of Health. No tenant shall use any machinery
which may cause any objectionable noise, jar, or tremor to the floors or walls,
or which, by its weight, might injure the floors of the Building. No tenant
shall do anything in the Leased Premises and/or the Building which will pose a
risk of a Release of a Hazardous Substance or creation of an Environmental
Condition on the Leased Premises.

4.   NO AUCTIONS. No tenant shall conduct any auction on the Leased Premises. No
tenant shall store goods, wares or merchandise on the Leased Premises, except
for such tenant's own personal use.

5.   MOVING. All freight, furniture, fixtures and equipment must be moved into,
within, and out of the Building under the supervision of the Landlord, and
according to such regulations as determined by Landlord from time to time.

6.   TENANT REQUESTS. The requests of any tenant will be attended to only upon
written application at the office of the Building. Employees of Landlord shall
not perform any work, nor do anything outside of their regular duties unless
special written instructions from the Landlord are first had and obtained and no
employee shall admit any person (whether a tenant or otherwise) to any part of
the Building without specific instructions from the Landlord or Landlord's
agent.

7.   KEYS. All keys shall be obtained from the Landlord and all keys shall be
returned to the Landlord upon the termination or earlier expiration of this
Lease. No tenant shall change the locks, or install other locks, on the doors to
the Leased Premises or elsewhere without the written consent of Landlord.

8.   LOCKING OF LEASED PREMISES. Each tenant shall see that the windows and
doors of the Leased Premises are closed and securely locked before leaving the
Leased Premises and that all lights are properly turned off.

9.   NOTICE OF ACCIDENTS. Each tenant shall give Landlord prompt notice of any
accident to, or defects in, the Building, the Leased Premises, the plumbing,
electric wiring, heating or air conditioning so that the same may be attended to
promptly.

10.  JANITORIAL SERVICE. All cleaning and janitorial services for the building
and the Leased Premises shall be provided exclusively through Landlord.

11.  UTILITIES. No tenant shall use any method of heating or air conditioning
other than that supplied by Landlord.

12.  COOPERATION WITH LANDLORD. Each tenant shall cooperate with Landlord in
obtaining maximum effectiveness of the cooling system by closing drapes and
other window coverings when the sun's rays fall on the windows of the Leases
Premises. No tenant shall tamper with, alter or change the setting of any
thermostats or temperature control valves.

13.  CONTROL BY LANDLORD. Landlord reserves the right to exclude or expel from
the Building any person who, in the judgment of Landlord is intoxicated or under
the influence of liquor or drugs, or who shall in any manner act in violation of
any of the rules and regulations of the Building.

14.  SERVICES. All services to be provided by Landlord as specified shall be
subject to schedule change as Landlord shall deem necessary.

15.  PASSES. Landlord reserves the right to exclude from the Building at all
time, other than the reasonable hours of the generally recognized business day
as determined by Landlord, all persons who do not present a pass or other
identification acceptable to Landlord.

16.  CANVASSING. Canvassing, soliciting and peddling in the Building are
prohibited and each tenant shall cooperate to prevent such activities.

17.  HAND TRUCKS. There shall not be used in any space, or in the public halls
of the Building either by any tenant or others, any hand trucks except those
which are approved by Landlord in writing and which hand trucks are equipped
with rubber tires and side guards.

18.  PLUMBING. The toilets, wash basins and other plumbing fixtures shall not be
used for any purpose other than those for which they were constructed, and no
sweepings, rubbish, rags or other substance shall be thrown therein. All damage
resulting from any misuse of fixtures shall be borne by the tenant who, of whose
employees, agents or visitors shall have caused the same.

19.  VEHICLES, COOKING, PETS. No bicycles, vehicles or animals of any kind shall
be brought into or kept in or about the Leased Premises, and/or the Building
and, except for any restaurant tenant permitted by Landlord to do so, no cooking
shall be done or permitted by any tenant on the Leased Premises and/or the
Building except the preparation of coffee, tea, hot chocolate and similar items
for the Tenant, its employees and business visitors. No tenant shall cause or
permit any unusual or objectionable odors to escape from the Leased Premises.

20.  ADVERTISING. No tenant shall engage in advertising which, in Landlord's
opinion, tends to impair the reputation of the Building or its desirability.

21.  AMENDMENT. Landlord reserves the right at any time to rescind any one or
more of these rules and regulations, or to make such other and further
reasonable rules and regulations as in Landlord's judgment may from time to time
be necessary for the safety, care and cleanliness of the Leased Premises, the
Building and for the preservation of order therein.

                                       9
<PAGE>   13
22.  HEADINGS. The headings of the Paragraphs of these rules and regulations
are for convenience of reference only and shall not limit or define, in any way
the terms and provisions hereof.

23. PROHIBITIVE USES. No premises shall be used for manufacturing or for the
storage of merchandise except as such storage may be incidental to the use of
such premises for general office purposes. No tenant shall occupy or permit
any portion of its premises to be occupied for the manufacture or sale of
liquor, narcotics, or tobacco in any forms, or as a medical office, or as a
barber shop or manicure shop without the prior written consent of Landlord. No
tenant shall advertise for laborers giving an address at the Building. No
premises shall be used for lodging or sleeping or for illegal purposes.

24. COMBUSTIBLE MATERIALS AND HAZARDOUS SUBSTANCES. No tenant shall use or keep
in any premises or at the Building any kerosene, gasoline or inflammable or
combustible fluid or material or Hazardous Substances.

25. WINDOW COVERINGS. Tenant shall not place any coverings on the windows
without first obtaining Landlord's written consent. The acceptability of any
such covering shall be at Landlord's sole discretion.

26. EXTERIOR FURNITURE. Tenant shall not place any furnishings on the balconies
or patios of the Building.

DATED this 26 day of April, 2000

                             LANDLORD:

                             MISSOURI FALLS PARTNERS, AN ARIZONA PARTNERSHIP
                             BY: INSIGNIA/ESG, INC., A DELAWARE CORPORATION
                             AS AGENT

                             BY: /s/ Donald B. Mudd
                                --------------------------------------------

                             ITS: Director
                                 -------------------------------------------

                               RECEIPT BY TENANT

The undersigned Tenant hereby acknowledges receipt of a complete copy of the
foregoing rules and regulations.

DATED this 20th day of April, 2000

                             TENANT;
                              CSK Auto, Inc., an Arizona corporation

                             BY: Lon B. Novatt
                                --------------------------------------------
                                  Lon B. Novatt
                             ITS: Senior Vice President
                                 -------------------------------------------

                                       10

<PAGE>   14
                                   EXHIBIT A

2,987 square feet (u)
3,360 square feet (r)

[Floor Plan]

SUITE 100
---------------                      [ARROW LOGO]
NOT TO SCALE

drawing:             project:                                     [VJS AIA Logo]
 EXHIBIT              MISSOURI FALLS
----------------     -------------------------
job no::              SUITE 100
 00022                625 EAST MISSOURI                 VICTOR JOHN SPURLOCK AIA
----------------      PHOENIX, AZ 85012                 ------------------------
date:                -------------------------          2622 East Acoma Drive
03/31/00                                             Phoenix, Arizona 85032-4931
----------------                         602.482.3737 (voice)-602.482.3797 (fax)<PAGE>   1
                                                                   Exhibit 10.17

                            FIRST AMENDMENT TO LEASE

     THIS FIRST AMENDMENT TO THE LEASE FOR SUITE 450, made and entered into this
20th day of August, 2000 by and between Missouri Falls Partners, an Arizona
partnership, hereinafter referred to as Landlord and CSK Auto, Inc. An Arizona
Corporation hereinafter referred to as Tenant.

                                   WITNESSETH

     WHEREAS Landlord and Tenant entered into that certain lease ("Lease") dated
April 20th, 2000, for the premises commonly known as Suite 450 of the Missouri
Falls Building, located at 645 E. Missouri Avenue, Phoenix, Arizona; and

     WHEREAS Landlord and Tenant with to amend the Lease with respect to the
addition of Suite 350 and Suite 365 respectively, that certain expansion space
consisting of approximately 4,868 total rentable square feet of which the pro
rata share of the building is .026% (the "Expansion Space") more particularly
described by the cross-hatched area on Exhibit "A" attached hereto and made a
part hereof;

     NOW, THEREFORE, in consideration of the mutual covenants and conditions
contained herein, and for such other good and valuable consideration the receipt
and sufficiency of which are hereby acknowledged, Landlord and Tenant agree that
the said Lease shall be and is hereby amended as follows.

1.   Upon the conditions set forth herein, effective from and after September 1,
2000, the Lease shall be amended so that (1) the Premises shall be increased by
the Expansion Space, (2) the area of the Combined Premises of Suites 450, 365,
and 350 shall be stipulated for all purposes under the Lease to contain
approximately 17,304 rentable square feet and the tenant's proportionate share
of the building shall now be 9.24%, and;

2.   The commencement date for the Expansion Space shall be September 1, 2000,
and the term shall be coterminous with the Lease to terminate on October 31,
2006.

3.   The Expansion Space Monthly base rent for the term of the Lease will be as
follows:

     October 1, 2000 through October 31, 2001
     $8,519.00 per month ($21.00 per rentable square foot) plus applicable
     taxes.

     November 1, 2001 through October 31, 2006
     From November 1, 2001 through the end of the lease term, Base Rent per
     square foot for the Demised Premises shall be adjusted to an amount equal
     to the Base Rent in effect on October 31, 2001 multiplied by the lesser of
     (I) 115%, and (ii) the Cumulative CPI Factor for the period from November
     1, 1996 through October 31, 2001. There shall be no decrease in the Base
     Rent as a result of the adjustment contemplated by this paragraph of the
     Addendum.

     As used herein "Cumulative CPI Factor" shall mean a fraction, the numerator
     of which is the Current Number and the denominator of which is the Base
     Number. As used in this definition, the following capitalized terms shall
     mean: "Base Number" shall mean the Consumer Price Index for All Urban
     Consumers, United States City Average, All Items (1982-84=100), issued by
     the Bureau of Labor Statistics of the United States Department of Labor
     (hereinafter called the "Index") for the month immediately prior to the
     period in question; and "Current Number" shall mean the latest Index
     published for the last month of the period in question by the Bureau of
     Labor Statistics or other governmental agency then publishing the Index (or
     if the Index is no longer published, the index of consumer prices
     reasonably deemed by Landlord to be comparable to the Index), after making
     such adjustments as may be prescribed by the agency publishing the same or
     as otherwise so deemed to be required to compensate for changes subsequent
     to January 1, 1984 in the base, items included or method of compilation
     thereof.
<PAGE>   2
4.   The Operating Expense Base Year for the Expansion Space will be 2000.

5.   Landlord shall provide a Tenant Improvement and Architectural Allowance of
     Five and no one hundredths Dollars ($5.00) per square foot for improvements
     in the Expansion Space.

6.   In consideration for the making of this Lease, Landlord and Tenant do
     hereby mutually agree that Landlord shall provide Tenant with eighteen (18)
     covered unreserved spaces throughout the term of the lease.

     Except as amended herein, all of the terms and conditions in the above
defined Lease, shall remain in full force and effect.

     IN WITNESS WHEREOF, Landlord and Tenant have executed this First Amendment
to Lease as of the date hereinabove written.

TENANT                                 LANDLORD
CSK AUTO, INC.,                        Missouri Falls Partners,
an Arizona corporation                 an Arizona Partnership
                                       By: Insignia/ESG,
                                       A Delaware corporation as Agent

By: /s/ Lon Novatt                    By: /s/ [Illegible Signature]
   ------------------------               ----------------------------
        LON B. NOVATT
Its: SENIOR VICE PRESIDENT             Its: Executive Director
    -----------------------                ---------------------------
<PAGE>   3

                                  [Floor Plan]

                                          SUITE 370
                                          ---------------           [ARROW LOGO]
                                          NOT TO SCALE

drawing:             project:                                     [VJS AIA Logo]
       EXHIBIT A      MISSOURI FALLS
----------------     -------------------------
job no:               SUITE 370
                      625 EAST MISSOURI                 VICTOR JOHN SPURLOCK AIA
----------------      PHOENIX, AZ 85012                 ------------------------
date:                -------------------------          2622 East Acoma Drive
          8/9/00                                     Phoenix, Arizona 85032-4931
----------------                         602.482.3737 (voice)-602.482.3797 (fax)

<PAGE>   4
                                                             [INSIGNIA/ESG LOGO]

                                BASE YEAR LEASE

DATE: April 20, 2000
     -----------------------------------

LANDLORD: Missouri Falls Partners, an Arizona Partnership
         --------------------------------------------------------

TENANT: CSK Auto, Inc. An Arizona Corporation
        ---------------------------------------------------------

I.   LEASED PREMISES

     The leased premises (the "Leased Premises") are as shown on Exhibit "A"
     attached hereto are further defined as Suite #450 consisting of
     "approximately 12,436 rentable square feet".

     Twelve thousand four hundred thirty six square feet
     ---------------------------------------------------

II.  LEASE

     The Landlord hereby leases to the Tenant, and the Tenant hereby leases from
the Landlord, the Leased Premises, upon the terms and conditions set forth in
this Lease (the "Lease").

III. TERM

     This Lease is for a term of seventy-eight (78) months commencing May 1,
2000 (the "Commencement Date") and terminating October 31, 2006, (the
"Termination Date").

     If the Leased Premises or the Building in which the Leased Premises are
located are not completed at the Commencement Date and possession of the Leased
Premises is not delivered to Tenant by the Commencement Date, the Commencement
Date shall be the first day of the calendar month following the delivery of the
Leased Premises to Tenant. If the Leased Premises are delivered to Tenant and
Tenant accepts possession on any day earlier than the Commencement Date, the
rental for the interim shall be paid by Tenant on a prorata basis, but such
earlier taking of possession shall not change the Termination Date of this
Lease.

V.   RENTAL DEFINITIONS

     Tenant agrees to pay as base rental the amount of [See Addendum] ($)_______
per month (the "Base Rent") for each and every month of the Lease (plus any
excise, privilege or sales taxes levied on the rentals or the receipt thereof,
except Landlord's income tax), payable in advance, without offset or deduction,
on the first day of each month commencing with the Commencement Date of the
Lease.

     The Base Rent shall be subject to adjustment each calendar year to
compensate for increases in Landlord's "Operating Costs" (as hereinafter
defined). However, in no event, shall Tenant's Base Rent be less than the Base
Rent specified herein.

     [See Addendum]

     "Operating Costs" shall be determined on an accrual basis for each calendar
year by taking into account, on a consistent basis, all costs of management,
maintenance, and operation of the Building, including, but not limited to the
costs of cleaning, utilities, air conditioning and heating, plumbing, elevator,
insurance, ground rent, landscaping costs and the cost of any capital
improvements which are intended to reduce Operating Costs or improve safety, and
those capital improvements made to keep the Building in compliance with
governmental requirements applicable from time to time together with interest at
the Prime Rate (as hereinafter defined) on the unamortized portion of such cost,
amortized over such reasonable period as Landlord shall determine, and all other
costs which can properly be considered operating expenses incurred in the
management, maintenance and operation of the Building.

     The Operating Costs shall be determined for each calendar year. If the
Operating Costs for any calendar year exceed the Base Operating Cost, Tenant's
rent for said calendar year shall be increased by an amount equal to Tenant's
"Proportionate Share" (as hereinafter defined) of such excess which increased
rental for such calendar year Tenant agrees to pay to Landlord in accordance
with the statements rendered.

     Each calendar year Landlord may elect to require that the rental be
adjusted for that year effective January 1 on the basis of Landlord's estimates
of increases or decreases in Operating Costs, which adjusted rental Tenant
agrees to pay in accordance with the statements rendered. A final adjustment of
the rental for each calendar year shall be made the following year based upon
the final Operating Costs, determined as herein provided and examined by
Landlord's regularly employed accountants. Appropriate fair adjustments shall be
made for costs which vary with occupancy and where tenants pay costs that in
other leases are paid by Landlord. In no event, however, shall Tenant's rent be
less than the Base Rent specified above.

     Tenant hereby agrees to pay, as additional rent, Tenant's Proportionate
Share of any Rent and Personal Property taxes (as hereinafter defined) assessed
or levied for any tax year (the "Tax Year") or portion thereof occurring during
the term of this Lease in excess of the base taxes. If the Rent and Personal
Property taxes for any Tax Year are lower than the Base Taxes, Tenant shall not
be entitled to any refund whatsoever.

                                       1
<PAGE>   5
      After landlord has received the tax bill(s) for each tax year, landlord
shall furnish tenant with a written statement of the amount due as tenant's
proportionate share of real and personal property taxes in excess of the base
year taxes, and within thirty (30) days of the date of such statement, tenant
shall pay the amount due in one lump sum. Alternatively, Landlord shall have the
right to estimate Tenant's Proportionate Share of Real and Personal Property
taxes in excess of the Base Year Taxes, which sums Tenant agrees to pay in
accordance with the statements rendered, in which event a final annual
adjustment shall be made based upon the Real and Personal Property taxes
actually assessed or levied. The failure of Landlord to send Tenant any such
statement shall not constitute a waiver by Landlord of its right to require
Tenant to pay its Proportionate Share of such excess. Any fractional Tax Year in
the first or final year of the Lease term shall be treated proportionately on a
three hundred sixty (360) day year basis.

      For the purposes of this Paragraph V, Rental, Definitions, the following
terms shall have the following meanings:

      1. "Tax Year" shall mean the twelve (12) month period employed for real
and personal property taxation purposes by each of the taxing authorities in the
State of Arizona.

      2. "Real and Personal Property taxes" shall mean and include a) all real
property taxes and personal property taxes, charges and general and special
assessments which are levied or assessed upon or with respect to the Building,
and any improvements, fixtures, and equipment and all other personal property of
Landlord located on, in or about the Building and/or used in connection with the
operation thereof and b) all taxes which shall be levied or assessed in addition
to or in lieu of such real or personal property taxes, but shall not include any
net income, franchise, capital stock, estate or inheritance taxes.

      3. Tenant's "Proportionate Share" shall mean the ratio, expressed as a
percentage, of the rentable area of the Leased Premises to the rentable area of
the Building, which the parties hereby stipulate to be six and sixty five
hundredths percent (6.65%).

      4. As used in this Lease, the term "Building" includes the building and/or
buildings and adjoining parking areas, if any, and the land and/or air space
which is the site and grounds for such buildings and parking areas, regardless
of the name under which such buildings may be known.

      5. As used in this Lease, the term "Prime Rate" shall mean the sum of (a)
that rate of interest, charged by the Bank One, a national banking association
(or any successor to the business of such bank), and announced by such bank,
from time to time, as its "prime rate," and (b) two (2) percentage points above
the annual rate of interest specified in clause "(a)" immediately hereinabove.

      6. "Base Taxes" shall be the Real and Personal Property taxes assessed or
levied for the calendar year in which the Commencement Date occurs.

VII.  INITIAL CONSTRUCTION -- See Addendum

VIII. REPAIRS AND ALTERATIONS

     Landlord agrees to make all necessary repairs to the exterior walls,
exterior doors, windows and corridors of the Building. Landlord agrees to keep
the Building in a clean, neat and attractive condition. Landlord agrees to keep
all building standard equipment such as elevators, plumbing, heating, air
conditioning and similar equipment in good repair, but Landlord shall not be
liable or responsible for breakdowns or temporary interruptions in service when
reasonable efforts are used to restore service.

      Tenant agrees that it will pay for the cost of all repairs to the Leased
Premises not required above to be made by Landlord and be responsible for all
redecorating, remodeling, alteration and painting required by it during the
term of this Lease. Tenant shall pay for any repairs to the Leased Premises, or
the Building, made necessary by any negligence or carelessness of Tenant, its
agents employees contractors or invitees. Tenant agrees to maintain the Leased
Premises in a clean, neat and sanitary condition.

     Tenant may place partitions and fixtures and make improvements and other
alterations in the interior of the Leased Premises at Tenant's expense,
provided, however, that prior to commencing any such work Tenant shall first
obtain the written consent of Landlord to the proposed work and Landlord shall
have the right to review and approve all plans. Landlord may require that said
work be done by Landlord's own employees or under Landlord's direction but at
the expense of Tenant, and Landlord may, as a condition to consenting to such
work, require that Tenant give security that the Leased Premises will be
completed free and clear of liens and in a manner satisfactory to Landlord.
Notwithstanding the foregoing, any such improvements or alterations by Tenant
shall conform to and be in substantial accordance in quality and appearance with
the quality and appearance of the improvements in the remainder of the Building.
Any such improvements shall become the property of Landlord upon expiration or
sooner termination of this Lease. Tenant shall remove any movable furniture and
equipment upon termination of this Lease and shall deliver the Leased Premises
to Landlord in as good condition as received, broom clean, normal wear and tear
excepted. In the event Tenant receives consent of the Landlord and uses Tenant's
own contractor for any such improvements then Tenant must provide Landlord with
contractor's evidence of workers compensation and liability insurance in amounts
sufficient to Landlord and shall have acquired the necessary building permits
prior to commencing any such construction.

                                       2
<PAGE>   6
IX.  FIRE OR CASUALTY INSURANCE

     In the event that the Leased Premises covered by the usual form of fire
and extended coverage insurance are wholly or partially destroyed by fire or
other casualty rendering them untenantable, Landlord shall, to the extent of
insurance proceeds actually received by Landlord, rebuild, repair or restore
the Leased Premises to substantially the same condition as when the same were
furnished to Tenant and this Lease shall remain in effect during such period.
In the event of total destruction, rent shall abate during the period of
reconstruction, and in the event of partial destruction, rent shall abate
prorata during the period of reconstruction. In the event, however, that the
building containing the Leased Premises is damaged or destroyed to the extent
of more than one-third (1/3) of its replacement cost, Landlord may elect to
terminate this Lease.

     Tenant shall be responsible for and shall provide Tenant's own insurance
coverage, and supply Landlord with evidence of such coverage with respect to
any furniture, fixtures, improvements, betterments, equipment, and personal
property belonging to Tenant and placed by Tenant in or upon the Leased
Premises. Tenant agrees and warrants to Landlord that any fire insurance
policy, extended coverage policy, casualty and loss policy, or other policy or
politics carried by Tenant in connection with this Lease or the Leased Premises
and/or insuring Tenant's property or effects located in or upon the Leased
Premises shall each contain a provision whereby the insurance carrier waives
any right of subrogation against the Landlord.

     Provided Landlord can obtain such waiver of subrogation rights with regard
to policies of fire or casualty insurance obtained by Landlord with regard to
the Building, Landlord hereby releases and waives any and all rights of
subrogation against Tenant which, in the absence of this release and waiver,
would arise in favor of any insurance company insuring Landlord against loss by
fire, extended coverage casualty and loss of any other type, resulting from
damage to or destruction of the building of which the Leased Premises form a
part or any portion thereof or in damage in or destruction of the property of
Landlord in the Building. Landlord shall not be required to obtain such
insurance policies except through insurance companies satisfactory to the
Landlord and the holder of any mortgage covering the Leased Premises.

X.   USE OF LEASED PREMISES

     The Leased Premises are leased to Tenant for the sole purpose of general
offices and for no other purpose whatsoever. Tenant agrees that it will use the
Leased Premises in such manner as to not interfere with or infringe upon the
rights of other tenants in the Building. Tenant agrees to comply with all
applicable Laws, ordinances and regulations ("Laws") in connection with its use
of and/or transfer of any interest in the Leased Premises and in performing all
repairs, remodeling and alterations to the Leased Premises, including all
Environmental Laws and obtaining all necessary permits, licenses or other
authorizations required pursuant to such Laws. Tenant shall supply all
documentation regarding compliance with the Laws, including written
documentation by the appropriate governmental authority evidencing compliance
with all such Laws.

XI.  SIGNS

     Landlord shall retain absolute control over the exterior appearance of the
Building and the exterior appearance of the Leased Premises as viewed from the
public halls. Tenant will not install, or permit to be installed, any drapes,
shutters, signs, lettering, advertising, or any items that will in any way
alter the exterior appearance of the Building or the exterior appearance of the
Leased Premises as viewed from the public halls or exterior of the Building.

XII. CONFIDENCE REPOSED IN TENANT AND TENANT'S REPRESENTATIONS AND WARRANTIES

     It is agreed that one of the conditions inducing Landlord to make this
Lease is the personal confidence reposed by it in Tenant, combined with the
belief that Tenant will be a tenant and occupant satisfactory to Landlord and
the other occupants of the Building. Should Tenant vacate or abandon the Leased
Premises during the term hereof, Landlord, at Landlord's discretion, shall have
the right to cancel and terminate this Lease without obligation to Tenant.

     Tenant represents and warrants as follows:

     A. Tenant has never been in violation of or investigated for violation of
any Environmental Laws.
     B. Tenant will not engage in any activity involving Hazardous Substances
or which could create an Environmental Condition on the Leased Premises or
permit any third party to do so, without Landlord's written consent.
     C. Tenant will immediately notify Landlord of (i) any investigation,
proceeding, notice or claim regarding a violation of any Environmental Law
relating to the Leased Premises or other premises which Tenant occupies, an
Environmental Condition on the Leased Premises, or a Release of Hazardous
Substances on the Leased Premises, (ii) any submissions or notifications made
by Tenant to governmental authorities or others concerning Environmental
Conditions or Hazardous Substances on the Leased Premises, and (iii) the
existence of any Hazardous Substances or Environmental Conditions on or about
the Leased Premises or on property adjoining or in the vicinity of the Leased
Premises that may be in violation of an Environmental Law (regardless of whether
Tenant is responsible for its existence). Tenant will take all appropriate
response actions in the event of an occurrence of an Environmental Condition on
the Leased Premises and shall resolve all environmental problems to the
satisfaction of Landlord. In the event of any investigation, notice of
violation or other action taken by a governmental agency or private person
relating in any way to Tenant's occupancy and use of the Leased Premises,
Tenant shall be solely responsible for complying with all legal requirements,
including cleanup of the Leased Premises, and requirements imposed by the
governmental authority. Tenant shall not, however take any remedial action in
response to the presence of any Hazardous Substance or Environmental Condition,
nor enter into any settlement agreement, consent decree or other compromise
without first notifying Landlord and affording Landlord ample opportunity to
appear, intervene, or otherwise appropriately assert and protect Landlord's
interests.

     D. Tenant will provide Landlord with an environmental audit at the end of
each Lease year, detailing the use, management and disposal of any Hazardous
Substances on the Leased Premises with the Environmental Laws.

     As used in this Lease, the following terms shall have the meanings
specified below:

     E. "Environmental Law(s)" shall mean any federal, state or local law,
including statutes, ordinances, rules, common law and guidelines, now in effect
or hereinafter enacted, pertaining to health, industrial hygiene, or the
environment, including without limitation, the Comprehensive Environmental
Response, Compensation and Liability Act, the Resource Conservation and
Recovery Act, the Toxic Substances Control Act, the Superfund Amendments and
Reauthorization Act, the Clear Air Act, the Federal Water Pollution Control
Act, the Safe Drinking Water Act, and the Solid Waste Disposal Act.

     F. "Hazardous Substances" shall mean any material, waste, or substance
which may or could pose risk of injury or threat to health or the environment
and any substance that is or becomes regulated by any federal, state or local
law.

     G. "Environmental Condition" shall mean any condition with respect to
soil, air, surface or groundwater which could require remedial action and/or
may result in claims, demands, and/or liabilities by or to third parties,
including without limitation, governmental entities.

     H. "Release" shall mean any releasing, spilling, leaking, pumping,
pouring, emitting, emptying, discharging, injecting, escaping, leaching,
disposing or dumping.

        Tenant's failure to perform or observe any of the above representations
and warranties shall constitute a breach of the Lease and shall entitle
Landlord to pursue any and all remedies allowed by law or at equity, including
without limitation canceling and terminating the Lease and imposing a rent
surcharge.

                                       3

<PAGE>   7
XIII.  ASSIGNMENT AND SUBLETTING

       A.   Tenant for itself, its heirs, distributees, successors and assigns,
expressly covenants that it shall not, by operation of law or otherwise, assign,
sublet, mortgage or encumber all or any part of this Lease or the Leased
Premises, including environmental liens in favor of a governmental entity, or
permit the Leased Premises to be used by others, without the prior written
consent of Landlord in each instance, which consent shall not be unreasonably
withheld. Any attempt by the Tenant to do any of the foregoing shall be null,
void and of no force or effect whatsoever. The consent by Landlord to any
assignment, sublet, mortgage or encumbrance or use of all or any part of the
Leased premises by others, shall not constitute a waiver of Landlord's right to
withhold its consent to any other assignment, sublet, mortgage, or encumbrance
or use of all or any part of the Leased Premises by others. Without the prior
written consent of Landlord, this Lease and the interest of Tenant therein or
any assignee of Tenant therein, shall not pass by operation of law, and shall
not be subject to garnishment or sale under execution in any lawsuit or
proceeding which may be brought against or by Tenant or any sublessee or
assignee of Tenant.

       B.   If Tenant requests Landlord's consent to an assignment of this Lease
or subletting of all or any part of the Leased Premises, Tenant shall submit to
Landlord: (1) the name of the proposed assignee or subtenant, (2) the terms of
the proposed assignment or subletting, (3) the nature of the proposed
subtenant's or assignee's business; and (4) such information as to such
subtenant's or assignee's financial responsibility and general reputation as
Landlord may require.

       C.   Upon the receipt of the request pursuant to Paragraph XIII(B)
hereinabove and information from Tenant, Landlord shall have the option, at
Landlord's discretion, to be exercised in writing within thirty (30) days after
such receipt, to either (1) cancel and terminate this Lease, if the request is
to assign or sublet all of the Lease and/or the Leased Premises or, if the
request is to sublet or assign a portion of the Lease and/or the Leased
Premises, to cancel and terminate this Lease with respect to such portion, in
each case as of the date set forth in Landlord's notice of exercise of such
option; (2) to grant said request, or (3) deny said request if Landlord finds
such proposed subtenant or assignee unacceptable.

       D.   In the event Landlord shall elect to cancel and terminate this
Lease, Tenant shall surrender possession of the Leased Premises, or the portion
of the Leased Premises which is the subject of the request, as the case may be,
on the date set forth in such notice in accordance with the provisions of this
Lease relating to surrender of the Leased Premises. If the lease shall be
canceled as to a portion of the Leased Premises only, the rent and other charges
payable by Tenant hereunder shall be reduced proportionately according to the
ratio that the number of rentable square feet in the portion of space
surrendered bears to the rentable square feet of space at the initial Leased
Premises.

       E. In the event that Landlord shall consent to a sublease or assignment
pursuant to the request from Tenant, Tenant shall cause to be executed by its
assignee or subtenant an agreement satisfactory to Landlord, whereby such
assignee or subtenant agrees to perform faithfully and to assume and be bound by
all of the terms, covenants, provisions and agreements of this Lease for the
period covered by the assignment or sublease and to the extent of the space
sublet or assigned. In addition, Tenant agrees that with regard to each such
sublease or assignment so consented to by Landlord, Tenant shall not assign or
sublet the premises to another existing tenant in the building housing the
Leased Premises. Tenant: (1) will not collect more than one month's rent in
advance, (2) will not terminate or cancel such sublease or assignment without
Landlord's prior written consent, (3) will be responsible for all the acts and
omissions of said sublessees or assignees, (4) will only sublease at the rental
which Tenant is then paying to Landlord, (5) shall pay to Landlord promptly,
following receipt of the amount of the value of any consideration received by
Tenant from any assignment of this lease, (6) An executed copy of each sublease
or assignment and assumption of performance by the sublessee or assignee, on
Landlord's standard form, shall be delivered to Landlord within five (5) days
prior to the commencement of occupancy set forth in such assignment or sublease.
No such assignment or sublease shall be binding on landlord until Landlord shall
have actually received such copies as required herein.

       F.   In no event shall any assignment or subletting to which Landlord may
consent, release or relieve Tenant from its obligations to fully perform all of
the terms, covenants and conditions of this Lease on its part to be performed.

       G.   In the event this Lease is canceled and terminated at Landlord's
option as provided hereinabove, neither of the parties shall have any further
obligations hereunder, except as may be expressly provided herein and except
Tenant shall pay all rents, charges and all other amounts due, as set out in the
Lease, to the effective date of such cancellation.

XIV.   EMINENT DOMAIN

       In the event any portion of the Leased Premises is taken from Tenant
under eminent domain proceedings, Tenant shall have no right, title or interest
in any award made to Landlord for such taking.

XV.    WAIVER AND SEVERABILITY

       The consent of the Landlord in any instance to any variation of the terms
of the Lease, or the receipt of rent with knowledge of any breach, shall not be
deemed to be a waiver by Landlord as to any breach of any covenant or condition
herein contained, nor shall any waiver be claimed as to any provisions of this
Lease unless the same be in writing and signed by Landlord. This Lease and any
written amendment, exhibits or addenda hereto contain the entire agreement
between the parties. If any term or provision of this Lease or any application
thereof shall be invalid or unenforceable, then the remaining terms and
provisions of this Lease and any other application of such term or provision
shall not be affected thereby.

XVI.   USE OF COMMON FACILITIES

       All elevators, stairways, halls and areas for the common use of all
tenants at the Building shall be open to reasonable use by Tenant, its
customers, clients and employees. Tenant and its officers, agents and employees
agree to park their motor vehicles only in areas designated from time to time
for that purpose or otherwise as permitted in writing by Landlord.

XVII.  SERVICES

       A.  Landlord agrees to provide air conditioning, heat, water and
electricity for lighting and normal office usage during the customary business
hours of the Building as established by Landlord, and to provide janitor
services of the type customarily furnished by comparable buildings, which shall
consist essentially of a nightly clean-up five (5) days per week, the costs of
which shall be includable in Operating Costs hereunder.

       B.  Tenant agrees to pay for all utilities and other services and
expenses used or incurred by Landlord on Tenant's behalf not specifically
provided for above.

XVIII. ENTRY OF LANDLORD

       Landlord reserves the right, without abatement of rent or other charges
due hereunder from Tenant, to enter upon or have its agent enter the Leased
Premises at reasonable times for the inspection of the same, including
environmental assessments and audits, to make necessary repairs, including any
actions necessary to remediate, abate or cleanup any Hazardous Substances or
Environmental Conditions on the Leased Premises, the cost of which Tenant will
be responsible for pursuant to paragraph XXVI below, to post notices of
non-responsibility and Landlord reserves the right, during the last six (6)
months of the term of this Lease to show the Leased Premises, at reasonable
times, to prospective purchasers or tenants.

       Tenant hereby waives any claim for damages for any injury or
inconvenience to or interference with Tenant's business, any loss of occupancy
or quiet enjoyment of the Leased Premises, and any other loss occasioned by
Landlord's entry. Landlord shall at all times have and retain a key with which
to unlock all of the doors in, upon and about the Leased Premises, excluding
Tenant's vaults and safes (as the same are permitted by Landlord to be upon the
Leased premises), and Landlord shall have the

                                       4

<PAGE>   8
right to use any and all means which Landlord may deem proper to open said doors
in an emergency in order to obtain entry to the Leased Premises and any entry
into the Leased Premises obtained by Landlord by any of said means, or
otherwise, shall not under any circumstances be construed on deemed to be a
forcible or unlawful entry into, or a detainer of, the Leased Premises or an
eviction of Tenant from the Leased Premises or any portion thereof.

XX.  SUBORDINATION AND ATTORNMENT

          Landlord reserves the right to place liens and encumbrances on the
Leased Premises superior in lien and effect to this Lease. This Lease and any
and all renewals, modifications, replacements or extensions thereof, at the
option of the Landlord, shall be subject and subordinate to any liens and
encumbrances now or hereinafter imposed by Landlord upon the Leased Premises on
the Building and Tenant agrees to execute and deliver upon demand (and to cause
all sublessees and assignees under Tenant to execute and deliver upon demand)
such instruments subordinating this Lease (and all subleases and assignments
pursuant to this Lease) to any such lien on encumbrance as shall be required by
Landlord.

          In the event Landlord's interest in the Leased Premises is derived
from a lease from another party and said Lease should be terminated by the other
party, Tenant agrees to attorn (and to cause all sublessees and assignees under
Tenant to so attorn) to the other party, its successors and assigns as Landlord
on this Lease.

          In the event any proceedings are brought for the foreclosure of any
mortgage on the Leased Premises, Tenant will attorn (and Tenant will cause all
sublessees and assignees under Tenant to so attorn) to the purchaser at
foreclosure sale and recognize the purchaser as the Landlord under this Lease.
The purchasers by virtue of such foreclosure shall be deemed to have assumed, as
substitute Landlord, the terms and conditions of this Lease until the resale or
other disposition of its interest by such purchaser. Such assumption, however,
shall not be deemed of itself an acknowledgement by the purchaser of the
validity of any then existing claims of Tenant (or the claims of any sublessees
or assignees under Tenant) against the prior Landlord.

          Tenant agrees to execute and deliver (and to cause all sublessees and
assignees under Tenant to execute and deliver) such further assurance and other
documents (including but not limited to a new lease upon the same terms and
conditions as this lease) continuing the foregoing as such purchaser may
reasonably request. Tenant on behalf of itself and on behalf of all sublessees
and assignees under Tenant waives any right of election to terminate this
Lease because of any such foreclosure proceedings. Tenant hereby irrevocably
constitutes and appoints Landlord as Tenant's attorney-in-fact to execute (and
to deliver to any third party) any documents hereinabove required to be executed
by Tenant, for and on behalf of Tenant, if Tenant shall have failed to do so
within ten (10) days after the request therefor by Landlord.

XXI.      NOTICES

          Any notices or demands to be given hereunder shall be in writing and
shall be given to Landlord and to Landlord's managing agent with regard to the
Building, at their respective offices and to Tenant at the Leased Premises, and
shall be by registered or certified United States mail, postage prepaid or, at
the election of Landlord, hand delivered.

XXII.     DEFAULT

          In the event Tenant fails to pay any rental due hereunder or fails to
keep and perform any of the other terms or conditions hereof, time being of the
essence, then five (5) days monetary and fifteen (15) days non monetary after
written notice of default given to Tenant from Landlord, the Landlord may, if
such default has not been contacted, resort to any and all legal remedies on
combination or remedies which Landlord may desire to assert including but not
limited to one or more of the following: (1) lock the doors to the Leased
Premises and exclude Tenant therefrom, (2) retain or take possession of any
property on the Leased Premises pursuant to Landlord's statutory lien, (3) enter
the Leased Premises and remove all persons and property therefrom, (4) declare
this Lease at an end and terminated, (5) sue for the rent due and to become due
under this Lease, and for any damages sustained by Landlord, (6) collect,
directly from any sublessee or assignee under Tenant all subrents and other
charges payable by such sublessees or assignees, Tenant hereby assigning to
Landlord such subrents and other charges in the event of a default by Tenant
under this Lease, and (7) continue this Lease in effect and relet the Leased
Premises on such terms and conditions as Landlord may deem advisable with Tenant
remaining liable for the monthly rent plus the reasonably cost of obtaining
possession of the Leased Premises and of any repairs and alterations necessary
to prepare the Leased Premises for reletting, less the rentals received from
such reletting, if any. No action of Landlord shall be construed as an election
to terminate this Lease unless written notice of such specific intention be
given to Tenant. Tenant agrees to pay as additional rental all attorney's fees
and other costs and expenses incurred by Landlord in enforcing any of Tenant's
obligations under this Lease whether or not legal action is commenced on
judgement obtained. Any amount due from Tenant to Landlord under this Lease
which is not paid when due shall bear interest at the "Prime Rate" that is in
effect on the date such amount is due, accruing from such date until paid.
Furthermore, that rate of interest paid by Tenant on any such amount shall be
adjusted as the "Prime Rate" is adjusted.

XXIII.    LATE PAYMENTS.

          Tenant hereby acknowledges that the late payment by Tenant to Landlord
of rent or any additional rent or other sums due hereunder will cause Landlord
to incur costs not contemplated in this Lease, the exact amount of which will be
extremely difficult and impracticable to ascertain. Such costs include but are
not limited to processing, administrative and accounting costs.

          Accordingly, if any installment of rent or any additional rent or any
other sum due from Tenant shall not be received by Landlord within ten (10) days
after written notice of such delinquency, Tenant shall pay to Landlord a late
charge equal to three percent (3%) of such overdue amount. The parties hereby
agrees that such late charges represent a fair and reasonable estimate of the
costs Landlord will incur by reason of late payment by Tenant. Neither
assessment nor acceptance of such late charge by Landlord shall constitute a
waiver of Tenant's default with respect to such overdue amount, nor prevent
Landlord from exercising any of the other rights and remedies granted under the
Lease. Nothing contained in this paragraph shall be deemed to condone,
authorize, sanction or grant to Tenant an option for the late payment of rent,
and Tenant shall be deemed in default in the payment of its rent should the same
not be paid by the date on which it is due.

XXIV.     BUILDING RULES AND REGULATIONS

          Tenant agrees to abide by all rules and regulations ("currently in the
form attached hereto") of the Building Imposed by Landlord. Such rules and
regulations are imposed for the cleanliness, good appearance, proper
maintenance, good order and reasonable use of the Leased Premises and the
Building, and as may be necessary for the proper enjoyment of the Building by
all Tenants and their clients, customers and employees. The rules and
regulations may be changed from time to time upon ten (10) days notice to Tenant
provided such rules and regulations do not conflict with any provisions of this
lease. Tenant must ???????. Breach of the rules and regulations of the Building
shall not be grounds for termination of the Lease

                                       5
<PAGE>   9
unless Tenant continues to breach the same after ten (10) days written notice is
given by Landlord. Landlord shall not be responsible to Tenant for
nonperformance by any tenant or occupant of the Building of any rules or
regulations.

XXV.      LIENS
          Tenant shall keep the Landlord, Leased Premises and building harmless
from and against any liens or claims arising out of any work performed,
materials furnished or obligations incurred by Tenant, and shall indemnify and
hold Landlord harmless against the same, together with all costs of suit and
attorney's fees incurred by Landlord in connection therewith.

XXVI.     INDEMNIFICATION OF LANDLORD
          Landlord shall not be liable to Tenant, and Tenant hereby waives all
claims against Landlord for any injury (including death) or damage to any
person or property in or about the Leased Premises by or from any cause
whatsoever and Tenant shall indemnify and hold Landlord, its successors,
officers and employees harmless from any and all claims, costs, expenses or
liability of any kind (including without limitation a decrease in the value of
the Leased Premises and reasonable consultants' and attorneys' fees) arising
directly or indirectly from: (i) injury (including death) or damage to any
person or property whatsoever occurring on or about the Leased Premises, (ii)
Hazardous Substances or an Environmental Condition on or about the Leased
Premises, or (iii) violations or claims of violations by Tenant of an
Environmental Law. This indemnification obligation shall be in addition to any
other obligations and liabilities Tenant may have to Landlord at law or equity,
and shall survive the term of this Lease and shall not be subject to any other
provisions of this Lease that operate to limit Tenant's liability.
          Tenant shall obtain and keep in effect during the term of this Lease
a policy of comprehensive liability insurance, including public liability and
property damage, with a minimum combined single limit of liability of One
Million Dollars ($1,000,000.00). Said policy or policies shall name Landlord
and its agents as additional insureds and shall be issued by an insurance
company, licensed to do business in the State of Arizona, and acceptable to
Landlord. Said policy or policies shall additionally provide that the insurance
shall not be canceled or modified unless thirty (30) days prior written notice
has been given to Landlord. Tenant shall supply Landlord with a certificate of
the insurance which it has obtained prior to its occupation of the Leased
Premises. Landlord shall have the right to request Tenant to provide additional
insurance or other form of security satisfactory to Lender in the event that
Tenant's activities on the Leased Premises involve Hazardous Substances.

XXVII.    TAXES
          Tenant agrees to pay or cause to be paid, before delinquency, any and
all taxes levied or assessed and which become payable during the term hereof
upon all of Tenant's equipment, furniture, fixtures and other personal property
located in the Leased Premises.

XXVIII.   HOLDING OVER
          Upon the expiration or earlier termination of this Lease, Tenant shall
immediately surrender the Leased Premises to Landlord, such Leased Premises to
be broom clean, in good condition and repair, ordinary wear and tear excepted.
Upon Tenant's written request and Landlord's approval, Tenant may become a
Tenant on a month to month basis if Tenant remains in the premises upon Lease
expiration. Tenant shall be responsible for all monetary obligations pursuant to
the Lease agreement that existed for the month prior to such expiration, or
until Landlord shall adjust the monthly rent with thirty (30) days written
notice. If the Tenant or any sublessee or assignee under Tenant holds over after
the expiration or earlier termination of this Lease without Landlord's express
written consent, Tenant shall be in default hereunder and in addition to all of
the rights or remedies available to Landlord, Tenant shall be obligated to pay
to Landlord rent at double the rate in effect immediately prior to such holdover
with regard to the Leased Premises for the time during which Tenant retains
possession, which payment shall not constitute a waiver of any of Landlord's
other rights or remedies provided herein.

XXIX.     INSOLVENCY OR BANKRUPTCY
          Either (a) the appointment of a receiver to take possession of all or
substantially all of the assets of Tenant; or (b) an assignment by Tenant for
the benefit of creditors; or (c) any action taken or suffered by Tenant under
any insolvency, bankruptcy or reorganization net, shall constitute a default and
breach of this Lease by Tenant. Upon the happening of any such event, Landlord
shall have all the rights herein provided in the event of any such default or
breach, including without limitation the right, at Landlord's option, to
terminate this Lease and enter the Leased Premises and remove all persons and
property therefrom. In no event shall this Lease be assigned or assignable by
operation of law or by voluntary or involuntary bankruptcy proceedings or
otherwise and in no event shall this Lease or any rights or privileges hereunder
be an asset of Tenant under any bankruptcy, insolvency or reorganization
proceedings.

XXX.      SALE BY LANDLORD
          In the event of a sale or conveyance by Landlord of the Leased
Premises, the Building, or in the building in which the Leased Premises are
situated, the same shall operate to release landlord from any further liability
upon any of the covenants or conditions, express or implied, herein contained
in favor of Tenant and in such event Tenant agrees to look solely to the
responsibility of the successor in interest of Landlord in and to this Lease.
This Lease shall not be affected by any such sale, and Tenant agrees to attorn
to the purchaser or assignee upon Landlord's request. Tenant shall deliver to
such purchaser an offset statement and an estoppel certificate in such form as
Landlord may request, and, in the event Tenant fails to deliver said statement
and certificate within ten (10) days after demand by Landlord, Tenant hereby
constitutes and appoints Landlord as Tenant's attorney-in-fact to execute said
statement and certificate. Tenant's failure to deliver an estoppel certificate
to Landlord as required herein shall be conclusive evidence against Tenant that
this Lease, with any amendments identified by Landlord, is in full force and
effect, that there are no uncured defaults by Landlord, that no more than one
month's rental has been paid in advance and that Tenant has no claims or
offsets against Landlord.

XXXI.     ATTORNEY'S FEES
          In the event of any action or proceeding brought by either party
against the other under this Lease, the prevailing party shall be entitled to
recover its attorney's fees and costs in such action or proceeding. In the
event Landlord intervenes in or becomes a party or is made a party to any
action or proceeding arising in connection with this Lease in order to protect
its rights, then Tenant shall pay to Landlord the fees of Landlord's attorneys
therein as fixed by the court.

XXXII.    SURRENDER OF PREMISES
          The voluntary or other surrender of this Lease by Tenant, or a mutual
cancellation thereof, shall not work a merger, and shall, at the option of
Landlord, terminate all or any existing subleases or subtenancies, or may, at
the option of Landlord, operate as an assignment to Landlord of any or all such
subleases or subtenancies. Tenant agrees that there shall be no value to the
leasehold upon termination or cancellation of the Lease under its terms.

XXXIII.   LIMITATION OF LANDLORD'S LIABILITY
          Tenant covenants and agrees that any claims that Tenant may have now
or hereafter against Landlord shall be asserted solely against and satisfied
only out of Landlord's right, title and interest in the Building and not from
any other thing or asset of Landlord. In no event shall any officer, director,
employee, agent, shareholder, partner, member or beneficiary of Landlord be
personally liable for any of Landlord's obligations hereunder.

                                       6

<PAGE>   10
XXXIV.    TIME OF THE ESSENCE

          Time is of the respecting Tenant's performance of Tenant's obligations
pursuant to and in accordance with this Lease.

XXXV.     BINDING EFFECT

          The covenants and conditions herein contained shall, subject to the
provisions restricting Tenant's assignment and subletting, apply to and bind the
heirs, executors, administrators, personal representatives, successors and
assigns of the parties hereto.

XXXVI.    RECORDATION

          Tenant shall not record this Lease or any short form memorandum
thereof without the prior written consent of Landlord, which Landlord may
withhold in Landlord's sole, absolute and unfettered discretion.

XXXVII.   NAME OF BUILDING

          Tenant shall not use the name of the Building for any purpose other
than as an address of the business to be conducted by Tenant in the Leased
Premises.

XXXVIII.  GOVERNING LAW

          This Lease and all the terms and conditions thereof shall be governed
by the laws of the State of Arizona.

XXXIX.    DEFINED TERMS AND PARAGRAPH HEADINGS

          The words "Landlord" and "Tenant" as used herein shall include the
plural as well as the singular. Words used in masculine gender include the
feminine and neuter. If there is more than one Tenant, the obligations hereunder
imposed upon Tenant shall be joint and several. The paragraph headings and
titles to the paragraphs of this Lease are not a part of this Lease and shall
have no effect upon the construction or interpretation of any part thereof.

XXXX.     WAIVER OF TRIAL BY JURY; CONSENT TO JURISDICTION AND VENUE

          EACH PARTY HEREBY WAIVES TRIAL BY JURY IN THE EVENT OF ANY LEGAL
PROCEEDING BROUGHT BY THE OTHER IN CONNECTION WITH THIS LEASE. EACH PARTY SHALL
BRING ANY ACTION AGAINST THE OTHER IN CONNECTION WITH THIS LEASE IN A FEDERAL OR
STATE COURT LOCATED IN MARICOPA COUNTY, ARIZONA; EACH PARTY CONSENTS TO THE
JURISDICTION OF SUCH COURTS; AND, EACH PARTY WAIVES TO ANY RIGHT TO HAVE ANY
PROCEEDING TRANSFERRED FROM SUCH COURTS ON THE GROUNDS OF IMPROPER VENUE OR
INCONVENIENT FORUM.

CSK AUTO, INC., an Arizona corporation
--------------------------------------- ---------------------------------------
          Name of Tenant                             Name of Landlord
                                                     Agent for Advisor

By: /s/ Lon B. Novatt                   By: /s/ Donald B. Mudd
   ------------------------------------    ------------------------------------
   Lon B. Novatt

Its: Senior Vice President              Its: Director
    -----------------------------------      ----------------------------------

Date:   4/20/00                         Date:    4/26/00
     ----------------------------------      ----------------------------------

                                       7
<PAGE>   11
                             RULES AND REGULATIONS

1.   PUBLIC AREA.  All public areas of the Building, shall be under the sole and
absolute control of Landlord and Landlord shall have the exclusive right to
regulate, modify and control these areas.

2.   WIRING.  When electric wiring of any kind is introduced, it must be
connected as directed by the Landlord and no boring or cutting for wires will
be allowed except with the written consent of the Landlord. No apparatus, other
than normal office machines and equipment of any kind shall be connected with
the electric wiring of the Leased Premises and/or the Building without the
written consent of the Landlord.

3.   INCREASE IN RISK.  No tenant shall do anything in the Leased Premises,
and/or the Building or bring or keep anything therein, which will in any way
increase or tend to increase the risk of fire, or which shall conflict with the
regulations of the Fire Department or the fire laws, or with any rules or
ordinances established by the Board of Health. No tenant shall use any
machinery which may cause any objectionable noise, jar or tremor to the floors
or walls, or which, by its weight, might injure the floors of the Building. No
tenant shall do anything in the Leased Premises and/or Building which will pose
a risk of a Release of a Hazardous Substance or creation of an Environmental
Condition on the Leased Premises.

4.   NO AUCTIONS.  No tenant shall conduct any auction on the Leased Premises.

5.   MOVING.  All freight, furniture, fixtures and equipment must be moved into,
within, and out of the Building under the supervision of the Landlord, and
according to such regulations as determined by Landlord from time to time.

6.   TENANT REQUESTS.  The requests of any tenant will be attended to only upon
written application at the office of the Building. Employees of Landlord shall
not perform any work, nor do anything outside of their regular duties unless
special written instructions from the Landlord are first had and obtained and no
employee shall admit any person (whether a tenant or otherwise) to any part of
the Building without specific instructions from the Landlord or Landlord's
agent.

7.   KEYS.  All keys shall be obtained from the Landlord and all keys shall be
returned to the Landlord upon the expiration or earlier termination of this
Lease. No tenant shall change the locks, or install other locks, on the doors to
the Leased Premises or elsewhere without the written consent of Landlord.

8.   LOCKING OF LEASED PREMISES.  Each tenant shall see that the windows and
doors of the Leased Premises are closed and securely locked before leaving the
Leased Premises and that all lights are properly turned off, at the end of each
day.

9.   NOTICE OF ACCIDENTS.  Each tenant shall give Landlord prompt notice of any
accident to, or defects in, the Building, the Leased Premises, the plumbing,
electric wiring, heating or air conditioning so that the same may be attended
to promptly.

10.  JANITORIAL SERVICE.  All cleaning and janitorial services for the building
and the Leased Premises shall be provided exclusively through Landlord.

11.  UTILITIES.  No tenant shall use any method of heating or air conditioning
other than that supplied by Landlord.

12.  COOPERATION WITH LANDLORD.  Each tenant shall cooperate with Landlord in
obtaining maximum effectiveness of the cooling system by closing drapes and
other window coverings when the sun's rays fall on the windows of the Leased
Premises. No tenant shall tamper with, alter or change the setting of any
thermostats or temperature control valves.

13.  CONTROL BY LANDLORD.  Landlord reserves the right to exclude or expel
from the Building any person who, in the judgment of Landlord, is intoxicated
or under the influence of liquor or drugs, or who shall in any manner act in
violation of any of the rules and regulations of the Building.

14.  SERVICES.  All services to be provided by Landlord as specified shall be
subject to schedule change as Landlord shall deem necessary.

15.  PASSES.  Landlord reserves the right to exclude from the Building at all
time, other than the reasonable hours of the generally recognized business day
as determined by Landlord, all persons who do not present a pass or other
identification acceptable to Landlord.

16.  CANVASSING.  Canvassing, soliciting and peddling in the Building are
prohibited and each tenant shall cooperate to prevent such activities.

17.  HAND TRUCKS.  There shall not be used in any space, or in the public halls
of the Building, either by any tenant or others, any hand trucks except those
which are approved by Landlord in writing, and are equipped with rubber tires
and side guards.

18.  PLUMBING.  The toilets, wash basins and other plumbing fixtures shall not
be used for any purpose other than those for which they were constructed, and no
sweepings, rubbish, rags or other substance shall be thrown therein. All damage
resulting from any misuse of fixtures shall be borne by the tenant who, or whose
employees, agents or visitors, shall have caused the same.

19.  VEHICLES, COOKING, PETS.  No bicycles, vehicles or animals of any kind
shall be brought into or kept in or about the Leased Premises, and/or the
Building and, except for any restaurant tenant permitted by Landlord to do so,
no cooking shall be done or permitted by any tenant on the Leased Premises
and/or the Building except the preparation of coffee, tea, hot chocolate and
similar items for the Tenant, its employees and business visitors. No tenant
shall cause or permit any unusual or objectionable odors to escape from the
Leased Premises.

20.  ADVERTISING.  No tenant shall engage in advertising which, in Landlord's
opinion, tends to impair the reputation of the Building or its desirability.

21.  AMENDMENT.  Landlord reserves the right at any time to rescind any one or
more of these rules and regulations, or to make such other and further
reasonable rules and regulations as in Landlord's judgment may from time to
time be necessary for the safety, care and cleanliness of the Leased Premises,
the Building and for the preservation of order therein.

                                       9
<PAGE>   12
22.  HEADINGS. The headings of the Paragraphs of these rules and regulations are
for convenience of reference only and shall not limit or define, in any way the
terms and provisions hereof.

23.  PROHIBITIVE USES. No premises shall be used for manufacturing or for the
storage of goods, wares or merchandise except as such storage may be incidental
to the use of such premises for general office purposes. No tenant shall occupy
or permit any portion of its premises to be occupied for the manufacture or
sale of liquor, narcotics, or tobacco in any forms, or as a medical office, or
as a barber shop or manicure shop without the prior written consent of
Landlord. No tenant shall advertise for laborers giving an address at the
Building. No premises shall be used for lodging or sleeping or for illegal
purposes.

24.  COMBUSTIBLE MATERIALS AND HAZARDOUS SUBSTANCES. No tenant shall use or
keep in any premises or at the Building any kerosene, gasoline or inflammable or
combustible fluid or material or Hazardous Substances.

25.  WINDOW COVERINGS. Tenant shall not place any coverings on the windows
without first obtaining Landlord's written consent. The acceptability of any
such covering shall be at Landlord's sole discretion.

26.  EXTERIOR FURNITURE. Tenant shall not place any furnishings on the
balconies or patios of the Building.

DATED this 26th day of April, 2000.

                              Missouri Falls Partners, an Arizona Partnership
                              By: Insignia/ESG, Inc. a Delaware Corporation
                              as Agent
                              -----------------------------------------------
                                                Landlord

                              By: Donald B. Mudd
                              Its: Director

                               RECEIPT BY TENANT

The undersigned Tenant hereby acknowledges receipt of a complete copy of the
foregoing rules and regulations:

DATED this 20th day of April, 2000.

                              CSK Auto, Inc., an Arizona corporation
                              --------------------------------------
                                             Tenant

                              By:  /s/ Lon B. Novatt
                              Its: Senior Vice President

                                       10
<PAGE>   13
                                    ADDENDUM

This shall serve as an Addendum to that Lease dated April 20, 2000 by and
between Missouri Falls Partners, an Arizona partnership as Landlord, and CSK
Auto, Inc., an Arizona corporation, Tenant, for Suite 450 of the Missouri Falls
Building located at 645 East Missouri Ave, but the language contained herein
shall prevail if in conflict with any previous language.

1.   RENTAL SCHEDULE
     The first two- (2) months of the lease term the rent shall be free,
     thereafter it shall be as follows:

     JULY 1, 2000 THRU OCTOBER 31, 2001
     $20,726.67 per month ($20.00 per rentable square foot) plus applicable
     taxes

     NOVEMBER 1, 2001 THRU OCTOBER 31, 2006 From November 1, 2001 through the
     end of the lease term, Base Rent per square foot for the Demised Premises
     shall be adjusted to an amount equal to the Base Rent in effect on October
     31, 2001 multiplied by the lesser of (i) 115%, and (ii) the Cumulative CPI
     Factor for the period from November 1, 1996 through October 31, 2001. There
     shall be no decrease in the Base Rent as a result of the adjustment
     contemplated by this paragraph of the Addendum.

     A used herein "Cumulative CPI Factor" shall mean a fraction, the numerator
     of which is the Current Number and the denominator of which is the Base
     Number. As used in this definition, the following capitalized terms shall
     mean: "Base Number" shall mean the Consumer Price Index for All Urban
     Consumers, United States City Average, All Items (1982-84=100), issued by
     the Bureau of Labor Statistics of the United States Department of Labor
     (hereinafter called the "Index") for the month immediately prior to the
     period in question; and "Current Number" shall mean the latest Index
     published for the last month of the period in question by the Bureau of
     Labor Statistics or other governmental agency then publishing the Index (or
     if the Index is no longer published, the index of consumer prices
     reasonably deemed by Landlord to be comparable to the Index), after making
     such adjustments as may be prescribed by the agency publishing the same or
     as otherwise so deemed to be required to compensate for changes subsequent
     to January 1, 1984 in the base, items included or method of compilation
     thereof.

2.   SQUARE FOOTAGE

     Even though the Base Rent and other charges (the "Rent") set forth in this
     Lease is or may be calculated on a per square foot basis, the parties
     specifically acknowledge and agree that the amount of Rent which the Tenant
     is obligated to pay is for the space which it is leasing, regardless of the
     actual size of that space. (The Tenant acknowledges the Landlord's use of a
     load factor in the calculation of the square footage.) Therefore, if it is
     found that the actual square footage of the Demised Premises is more or
     less than the approximate square footage set forth in this Lease Agreement,
     the parties specifically understand and agree that the amount of Rent to be
     paid by the Tenant on a monthly basis shall not be adjusted either upward
     or downward. Furthermore, the Tenant's proportionate share, as defined in
     Article V, Section 3, shall not be adjusted either upward or downward if it
     is found that the Demised Premises contain more or less than the
     approximate square footage set forth in this Lease.

     Furthermore, Tenant agrees that it has no claims regarding rental
     overcharges under this or any other lease relating to the premises known as
     645 E. Missouri Avenue, Phoenix, AZ based on the calculation of square
     footage available to the tenant and Tenant agrees not to assert any claim
     based on the calculation of square footage under any existing lease
     regarding any period before or after the date hereof.

3.   OPERATING EXPENSES
     Landlord's "Base Operating Costs" shall mean the Operating Costs for the
     calendar year 1995.
<PAGE>   14
4.   PARKING
     In consideration for the making of this Lease, Landlord and Tenant do
     hereby mutually agree that Landlord shall provide Tenant with twenty-two
     (22) covered, reserved parking spaces and forty-five (45) covered
     unreserved spaces throughout the term of this lease.

5.   CONSTRUCTION
     Landlord agrees to pay Tenant within sixty (60) days of the full execution
     of this Lease, a construction allowance in the amount of Five Dollars
     ($5.00) per rentable square foot or Sixty-Two Thousand One Hundred Eighty
     and no/100 ($62,180.00) Dollars for improvements to the space.

6.   RIGHT TO LEASE SUITE 350 AND 365
     Landlord shall use its commercially reasonable efforts to relocate the
     current occupant of Suite 350 and Suite 365 (hereinafter the "Householder
     Group"), provided however that Landlord shall not be required to pay any
     money to relocate them. The square footage for Suite 350 and Suite 365
     amounts to respectively 2,914 and 1,954 rentable square feet (these two
     spaces shall hereinafter be referred to as the "Suites".) Once Householder
     Group has turned possession of the Suites back to the Landlord, Tenant
     shall within three (3) days thereafter provided that occupancy will be not
     later than August 31, 2000 provide Landlord with a lease signed by Tenant
     for the Suites (which shall have been prepared by Landlord) containing the
     same terms as herein, including without limitation, rental (based on Twenty
     One and no/100 ($21.00) Dollars per rentable square foot), increases in
     rent, term (to be contiguous with Tenant's other leases with Landlord),
     tenant improvement dollars (based on Five and no/100 ($5.00) Dollars per
     rentable square foot and one (1) month free rent to remodel the suites, and
     upon receipt of said lease signed by Tenant, Landlord shall sign and
     deliver a counterpart thereof to Tenant.

     Notwithstanding the foregoing, in the event Landlord fails to provide
     Tenant with possession of the Suites by August 31, 2000, then Tenant shall
     have the unilateral right, by providing Landlord with written notice, to
     terminate any rights and obligations it may have as specifically provided
     and granted herein by this Paragraph. In addition, Tenant shall be entitled
     to the same number of parking spaces as provided to the Householder Group
     in their Lease for the suites.

CSK AUTO INC.,                                       Missouri Falls Partners, an
an Arizona corporation                               Arizona partnership
                                                     By: Insignia/ESG a Delaware
                                                     Corporation as Agent

By: /s/ Lon B. Novatt                                By: /s/ Donald B. Mudd
   -------------------------                            ------------------------
    Lon B. Novatt                                        Donald B. Mudd

Its: Senior Vice President                           Its: Director
----------------------------                         ---------------------------

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