<PAGE>

                                                                Exhibit 10.29


             FIRST AMENDMENT TO TEN-YEAR INDUSTRIAL NET LEASE AGREEMENT
                                  (Building No. 2)


       This First Amendment to Office Lease ("Amendment") is entered into, 
and dated for reference purposes, as of June 9, 1998 by and between 
METROPOLITAN LIFE INSURANCE COMPANY, a New York corporation (herein referred 
to as "Metropolitan" or "Landlord"), as Landlord, and CYGNUS, INC., a 
Delaware corporation (herein referred to as "Cygnus" or "Tenant"), with 
reference to the following facts:

                                     RECITALS

       A.      Metropolitan's predecessor in interest as Landlord (Seaport 
Centre Venture Phase I, a California general partnership, herein, the 
"Venture") and Tenant's predecessor in interest as Tenant (Cygnus Research 
Corporation, a California corporation) entered into that certain written 
Lease dated September 27, 1988 (the "Lease"), for certain premises of 
approximately 37,856 square feet of space in Building 2 of Phase I ("Building 
2 Space"), whose current street address remains 400 Penobscot Drive, Redwood 
City, California, all as more particularly described in the Lease, which 
Lease included Rider No. 1 To Seaport Centre Standard Lease and Exhibits A, 
A-1& B, but did not include any Exhibit C which was inapplicable and was 
mistakenly listed as an attachment.

       B.      Met acquired and holds the interest of Landlord under the 
Lease.

       C.      Landlord and Tenant now desire to provide for extension of the 
term of the Lease of the entire Premises and other amendments of the Lease, 
all as more particularly provided herein.

       NOW, THEREFORE, in consideration of the foregoing, and of the mutual 
covenants set forth herein and of other good and valuable consideration, the 
receipt and adequacy of which are hereby acknowledged, the parties hereto 
agree as follows:

       SECTION 1.     DEFINED TERMS; PREMISES.  All capitalized terms not 
otherwise defined in this Amendment have the meanings set forth in the Lease 
unless the context clearly requires otherwise.  The term "Landlord" as used 
herein shall have the same meaning as and may be used interchangeably with 
the term "Lessor" in the Lease, and the term "Tenant" as used herein shall 
have the same meaning as and may be used interchangeably with the term 
"Lessee" in the Lease.  As used herein, the term "Premises" shall mean the 
Building 2 Space.

       SECTION 2.     TENANT'S INTEREST UNDER THE LEASE.  Tenant represents 
and warrants and agrees that: (i) Tenant occupies the Premises and is the 
Tenant under the Lease; (ii) Tenant is the successor in interest to Cygnus 
Research Corporation, a California corporation, and as such is the assignee 
of the interest of Tenant under the Lease, has assumed, or hereby assumes, 
the obligations of Tenant under the Lease, and holds all right, title and 
interest of Tenant under the Lease; (iii) has not entered into any assignment 
of the Lease, and no sublease or other agreement for use or occupancy of the 
Premises or any part thereof is in effect.  Tenant's obligations with respect 
to the representations, warranties and agreements under this Section survive 
the expiration or sooner termination of the Term of the Lease and of this 
Lease.

       SECTION 3.     EXTENSION OF TERM.  Landlord and Tenant acknowledge and 
agree that notwithstanding any provision of the Lease to the contrary, the 
Term of this Lease expires on December 10, 1998, and that the Term is hereby 
extended for the "Extended Term" commencing on December 11, 1998 (the 
"Extended Term Commencement Date") and expiring on December 10, 2003, unless 
sooner terminated pursuant to the terms of the Lease.  This extension is with 
respect to the entire Premises.  This extension is further upon and subject 
to the same conditions, terms, covenants and agreements contained in the 
Lease except as otherwise provided in this Amendment.  Landlord and Tenant 
acknowledge and agree that this Amendment provides all rights and obligations 
of the parties with respect to extension of the Term, whether or not in 
accordance with any other provisions, if any, of the Lease regarding renewal 
or extension, and

<PAGE>

without limiting the generality of the foregoing, Tenant and Landlord 
acknowledge and agree that the Option to Renew Lease Term set forth in 
Paragraph 2(b) of the Lease is null, void and of no force or effect, and that 
any extension beyond the Extended Term is governed by the Option to Extend 
set forth in Section 13 below.

       SECTION 4.     PREMISES LEASED "AS-IS"; CONSTRUCTION

                      (a)     AS-IS.  Notwithstanding any provision of the 
Lease to the contrary, Tenant acknowledges and agrees that (i) Tenant 
occupies the Premises and has investigated their condition to the extent 
Tenant desires to do so; (ii) Tenant hereby agrees that this Lease is of the 
Premises in its "AS IS" condition; (iii) no representation regarding the 
condition of the Premises or Building 2 has been made by or on behalf of 
Landlord; and (iv) Landlord has no obligation to remodel or to make any 
repairs (except as otherwise provided for in the Lease), alterations or 
improvements to the Premises or the building in connection with this 
Amendment or provide Tenant any allowance for any work by Tenant except to 
the extent of Landlord's Maximum Contribution, as provided below.

                      (b)     TENANT WORK GENERALLY.  Landlord and Tenant 
acknowledge and agree that notwithstanding any provisions of the Lease to the 
contrary:  (i) Tenant may desire to do certain repainting, recarpeting, 
remodeling, repair, improvement or alteration in connection with this 
Amendment, which for purposes of this Lease is referred to as the Tenant 
Work; (ii) all Tenant Work, if any, shall be done as alterations, additions 
or improvements of the Premises or any part thereof within the meaning of 
Paragraph 11 of the Lease ("Tenant Alterations"), subject to and in 
compliance with all conditions and provisions of the Lease applicable to 
Tenant Alterations, except as otherwise expressly provided herein; (iii) if 
the aggregate cost of the Tenant Work does not exceed the amount of 
Landlord's Maximum Contribution (defined below), Tenant shall not be required 
to obtain a completion and lien indemnity bond for it; and (iv) such work, 
including all design, plan review, obtaining all approvals and permits, and 
construction shall be at Tenant's sole cost and expense, except to the extent 
reimbursable out of Landlord's Maximum Contribution as provided below.

                      (c)     LANDLORD'S MAXIMUM CONTRIBUTION.  Landlord's 
Maximum Contribution shall mean an amount up to a maximum of One Hundred and 
Thirteen Thousand Five Hundred and Sixty-eight Dollars ($113,568.00) to 
reimburse Tenant for the actual costs of design, plan review, obtaining all 
approvals and permits, and construction of such Alterations (i) for the 
Premises, and/or (ii) for Alterations to Tenant's "Building 8 Space", at 701 
Galveston Street, Redwood City, California, or "Building 3 Space" at 501 
Chesapeake Street, Redwood City, California as both are defined and provided 
for in that certain third amendment of that certain Related Lease (as defined 
in the Lease) being executed concurrently herewith ("Related Amendment"), 
except for the additional amount of Landlord's Maximum Contribution provided 
in the Related Amendment.  In no event shall the Landlord's Maximum 
Contribution be used to reimburse any costs of designing, procuring or 
installing in the Premises any trade fixtures, movable equipment, furniture, 
furnishings, telephone equipment, cabling for any of the foregoing, or other 
personal property (collectively "Personal Property" for purposes of this 
Rider) to be used in the Premises by Tenant, and the cost of such Personal 
Property shall be paid by Tenant. Landlord's Maximum Contribution pursuant to 
this Amendment and that payable under the Related Amendment shall together be 
payable by Landlord to Tenant no more often than three times and no more 
often than one application every thirty (30) days, and otherwise follows:  
(a) for costs based upon the percentage of work completed prior to the date 
of application; and (b) in each case, any amount so payable shall be paid 
within 30 days after Landlord's receipt of Tenant's complete application for 
payment, which application shall include reasonable substantiation of costs 
incurred by Tenant, conditional lien releases to the extent of work 
completed, and full, final and unconditional lien releases upon completion of 
all Alterations (or, if the work is done under separate contracts or in 
smaller separate identifiable segments or phases, then upon completion of and 
with respect to each separate contract or phase).  Tenant shall keep full and 
correct accounts and shall exercise such control as may be necessary or 
appropriate for the proper financial management of the construction of the 
Alterations separately identified as to each of the Premises, the Building 8 
Space and the Building 3 Space and, if the work is done under separate 
contracts or in smaller separate identifiable segments or phases, then with 
respect to each separate contract or phase.  Provided further, Tenant must 
prior to October 1, 1999 submit

<PAGE>

all written applications with the items required above for disbursement or 
reimbursement for any reimbursable costsout of the Landlord's Maximum 
Contribution, and to the extent of any funds for which application has not 
been made prior to that date or if and to the extent that the reimbursable 
costs of the Tenant Work are less than the amount of Landlord's Maximum 
Contribution, then Landlord shall retain the unapplied or unused balance of 
the Landlord's Maximum Contribution and shall have no obligation or liability 
to Tenant with respect to such excess.

       SECTION 5.     MONTHLY BASE RENT FOR EXTENDED TERM COMMENCING UPON 
EXTENDED TERM COMMENCEMENT DATE.  Notwithstanding any provision of the Lease 
to the contrary, the amount of monthly base rent due and payable by Tenant 
for the Premises, accruing on and after the Extended Term Commencement Date 
and monthly thereafter for the Extended Term shall be as follows:

<TABLE>
<CAPTION>
         Period from/through          Monthly Total           Monthly Rate/Square Foot
       <S>                            <C>                     <C>
       12/11/1998 - 12/10/1999         $83,283.20                     $2.20
       12/11/1999 - 12/10/2000         $85,933.12                     $2.27
       12/11/2000 - 12/10/2001         $88,204.48                     $2.33
       12/11/2001 - 12/10/2002         $90,854.40                     $2.40
       12/11/2002 - 12/10/2003         $93,882.88                     $2.48
</TABLE>

       SECTION 6.     TENANT'S SHARE OF OPERATING EXPENSES.  Landlord and 
Tenant desire to set forth with greater particularity the components of 
operating expenses pursuant to Paragraph 7 of the Lease, and Tenant's 
proportionate share of such operating expenses allocated to Building 2, to 
Phase I and to the Project (defined below).  Notwithstanding any provision of 
the Lease to the contrary, during the Extended Term in addition to the base 
rent payable by Tenant, Tenant shall pay Tenant's proportionate share of all 
operating expenses as set forth below.  Operating expenses and exclusions 
therefrom are as defined in the Lease, except as otherwise provided below. 
Operating Expenses are not limited by references to the building in Paragraph 
7 of the Lease, but are determined with respect to and as allocable to the 
building in which the Premises is located, to Phase I and to the Project, and 
Tenant shall pay its proportionate share of such operating expenses, as 
follows:

               (i)    Tenant's proportionate share of Building Operating
       Expenses (defined below) of and attributable to Building 2 as of the
       date hereof equals one hundred percent (100%);
       
               (ii)   Tenant's proportionate share of Project Operating
       Expenses (defined below) is the percentage obtained by dividing the
       aggregate rentable square footage of the Premises located in the Project
       (defined below) by the total rentable square footage of the Project, and
       as of the date hereof equals seven and 44/1000 percent (7.044%);
       
               (iii)  Tenant's proportionate share of Phase Operating Expenses
       (defined below) of and attributable to Phase I, in which Building 2 is
       located, is the percentage obtained by dividing the aggregate rentable
       square footage of the Premises located in Phase I by the total rentable
       square footage of Phase I, and as of the date hereof equals twelve and
       542/1000 percent (12.542%);
       
               (iv)   operating expenses of and attributable to each building
       in which the Premises or part thereof is located includes all operating
       expenses that are directly and separately identifiable to the operation,
       maintenance or repair of such building and may also be referred to as
       "Building Operating Expenses" for each such building.  Tenant's
       proportionate share of Building Operating Expenses is the percentage
       obtained by dividing the rentable square footage of the Premises located
       in each building by the total rentable square footage of such building;
       
               (v)    operating expenses of and attributable to the Project
       ("Project Operating Expenses") includes all operating expenses with
       respect to the Project (defined below) that are not included as Phase
       Operating Expenses (defined below) and that are not either Building
       Operating

<PAGE>

       Expenses or operating expenses directly and separately identifiable to 
       the operation, maintenance or repair of any other leasable building 
       located in the Project, but Project Operating Expenses includes 
       operating expenses allocable to any areas of a building during such 
       time as such areas are made available by Landlord for the general 
       common use or benefit of the tenants of the Project, and their 
       employees and invitees, or the public, as such areas currently exist 
       and as they may be changed from time to time.  As of the date hereof, 
       "Project" means and consists of Phase I and Phase II of the 
       development commonly known as Seaport Centre in Redwood City, 
       California, and any expenses allocable to either pursuant to any 
       covenants, conditions and restrictions, or any reciprocal easements, 
       or any owner's association now or hereafter affecting them.  In the 
       event any building is added to or deleted from Tenant's Phase or any 
       Phase is added to or deleted from the Project which affects tenant's 
       proportionate share of either or both, Landlord shall recalculate 
       tenant's proportionate share as applicable;
       
               (vi)   operating expenses of a Phase ("Phase Operating
       Expenses") may include operating expenses that are directly and
       separately identifiable to the operation, maintenance or repair of each
       leasable building located in that Phase (including but not limited to
       Building Operating Expenses) and may include Project Operating Expenses
       that are separately identifiable to a Phase; and
       
               (vii)  Landlord shall have the right to allocate a particular
       operating expense as Building Operating Expenses, Project Operating
       Expenses or Phase Operating Expenses; however, in no event shall any
       portion of Building Operating Expenses, Project Operating Expenses or
       Phase Operating Expenses be assessed or counted against Tenant more than
       once.

       SECTION 7.     UTILITIES.  Landlord and Tenant desire to set forth 
with greater particularity the allocation of utilities expenses pursuant to 
Paragraph 8 of the Lease, and Tenant's proportionate share of such operating 
expenses allocated to the building in which the Premises is located, to Phase 
I and to the Project.  Notwithstanding any provision of the Lease to the 
contrary, excluding all utilities separately billed or metered to Tenant 
which shall be paid for solely and separately by Tenant, during the Extended 
Term in addition to the base rent and operating expenses payable by Tenant, 
Tenant shall pay Tenant's proportionate share of all utilities expenses as 
allocated and paid in the same proportionate share as set forth in Section 6 
of this Amendment regarding operating expenses.

       SECTION 8.     SECURITY DEPOSIT.  Notwithstanding any provision of 
Paragraph 6 of the Lease to the contrary, Landlord and Tenant acknowledge and 
agree that:  (a) as of the date hereof the only Security Deposit under the 
Lease held by Landlord is the security deposit of Thirty Thousand Five 
Hundred and Sixty-two Dollars ($30,562.00) held under the Related Lease, as 
amended, and that such amount is substituted for the reference to "Twenty 
Thousand Five Hundred Sixty-two Dollars ($20,562)" in Paragraph 6 of the 
Lease; and (b) except as modified above, the provisions of such Paragraph 6 
shall continue to apply.

       SECTION 9.     PARKING.  Landlord and Tenant acknowledge and agree 
that during the Extended Term the aggregate number of parking spaces provided 
for Tenant's use pursuant to Paragraph 30 of the Lease shall be one hundred 
and twenty-five (125) undesignated parking spaces.

       SECTION 10.    REMOVAL OF TENANT ALTERATIONS.  Upon the expiration or 
earlier termination of the Term of the Lease, including the Extended Term 
provided for in this Amendment, Tenant shall not be required to remove any of 
the alterations, additions or improvements to or of the Premises or any part 
thereof by Tenant for Tenant's initial occupancy under the Lease or made 
thereafter and still existing as of the date of this Amendment, provided that 
such alterations, additions or improvements were made in accordance with the 
applicable provisions of the Lease, as amended.  Landlord and Tenant 
acknowledge and agree that hereafter, all alterations, additions or 
improvements of the Premises or any part thereof within the meaning of 
Paragraph 11 of the Lease ("Tenant Alterations", as used in Section 4(b) of 
this Amendment), including Tenant Work, if any, as used in Section 4(b) of 
this Amendment, shall be subject to and in compliance with all conditions and 
provisions of the Lease applicable to Tenant Alterations, including the 
procedure set forth


<PAGE>

in the third paragraph of Paragraph 11 of the Lease to identify those Tenant 
Alterations which Tenant desires to remove at the end of the Lease term and 
those which Landlord will require Tenant to remove.

       SECTION 11.    BOOKS AND RECORDS.  Supplementing the second sentence 
of the third paragraph of Paragraph 7 of the Lease, as amended, the Tenant or 
its representative (which representative shall be a certified public 
accountant licensed to do business in the state in which the Property is 
located and whose primary business is certified public accounting) shall have 
the right, for a period of ninety (90) days following the date upon which 
Landlord furnishes Tenant with Landlord's statement accounting for actual 
costs of operating expenses (herein, "Landlord's Statement") is delivered to 
Tenant, to examine the Landlord's books and records with respect to the items 
in the foregoing statement of Operating Expenses during normal business 
hours, upon written notice, delivered at least three (3) business days in 
advance. If Tenant does not object in writing to Landlord's Statement within 
one hundred and twenty (120) days of Tenant's receipt thereof, specifying the 
nature of the item in dispute and the reasons therefor, then Landlord's 
Statement shall be considered final and accepted by Tenant.  Any amount due 
to the Landlord as shown on Landlord's Statement, whether or not disputed by 
Tenant as provided herein, shall be paid by Tenant when due within thirty 
(30) days after delivery of Landlord's Statement, as provided in Paragraph 7 
of the Lease, but such payment is without prejudice to any written exception 
Tenant may make pursuant to this Section.

       SECTION 12.    PARAGRAPH 38 OF THE LEASE.  Notwithstanding any 
provision of the Lease to the contrary, Paragraph 38 of the Lease is of no 
force or effect and is hereby deleted from the Lease.

       SECTION 13.    OPTION TO EXTEND.

       (a)     Landlord hereby grants Tenant a single option to extend the 
Extended Term of the Lease for an additional period of five (5) years (such 
period may be referred to as the "Option Term"), as to the entire Premises as 
it may then exist, upon and subject to the terms and conditions of this 
Section (the "Option To Extend"), and provided that at the time of exercise 
of such right:  (i) Tenant must be in occupancy of the entire Premises; and 
(ii) there has been no material adverse change in Tenant's financial position 
from such position as of the date of execution of the Lease, as certified by 
Tenant's independent certified public accountants, and as supported by 
Tenant's certified financial statements, copies of which shall be delivered 
to Landlord with Tenant's written notice exercising its right hereunder.

       (b)     Tenant's election (the "Election Notice") to exercise the 
Option To Extend must be given to Landlord in writing no earlier than the 
date which is two hundred and seventy (270) days before the Expiration Date 
and no later than the date which is two hundred and forty (240) days prior to 
the Expiration Date. If Tenant either fails or elects not to exercise its 
Option to Extend by not timely giving its Election Notice, then the Option to 
Extend shall be null and void.

       (c)     The Option Term shall commence immediately after the 
expiration of the Extended Term of the Lease.  Tenant's leasing of the 
Premises during the Option Term shall be upon and subject to the same terms 
and conditions contained in the Lease except that (i) the monthly base rent, 
plus payment of Tenant's proportionate share of Operating Expenses and 
Utilities charges pursuant to the Lease (in addition to all expenses paid 
directly by Tenant to the utility or service provider, which direct payments 
shall continue to be Tenant's obligation) shall be amended to equal the 
"Option Term Rent", defined and determined in the manner set forth in the 
immediately following Subsection; (ii) the Security Deposit provisions shall 
remain as provided in the Lease; (iii) Tenant shall accept the Premises in 
its "AS-IS" condition without any obligation of Landlord to repaint, remodel, 
repair (except as otherwise provided for in the Lease), improve or alter the 
Premises or to provide Tenant any allowance therefor; and (iv) there shall be 
no further option or right to extend the term of the Lease.  If Tenant timely 
and properly exercises the Option To Extend, references in the Lease to the 
Term shall be deemed to mean the Extended Term as extended by the Option Term 
unless the context clearly requires otherwise.

       (d)     The Option Term Rent shall mean the greater of (i) the monthly
base rent payable by Tenant under this Lease calculated at the rate applicable
for the last full month of the Extended Term,


<PAGE>

plus payment of Tenant's proportionate share of Operating Expenses and 
Utilities charges pursuant to the Lease (in addition to all expenses paid 
directly by Tenant to the utility or service provider, which direct payments 
shall continue to be Tenant's obligation) (collectively, "Preceding Rent") or 
(ii) the "Prevailing Market Rent".  As used herein Prevailing Market Rent 
shall mean the rent and all other monetary payments, escalations and triple 
net payables by Tenant, including consumer price increases, that Landlord 
could obtain from a third party desiring to lease the Premises for a term 
equal to the Option Term and commencing when the Option Term is to commence 
under market leasing conditions, and taking into account the following:  the 
size, location and floor levels of the Premises; the type and quality of 
tenant improvements; age and location of the Project; quality of construction 
of the Project; services to be provided by Landlord or by tenant; the rent, 
all other monetary payments and escalations obtainable for new leases of 
space comparable to the Premises in the Project and in comparable buildings 
in the mid-Peninsula area, and other factors that would be relevant to such a 
third party in determining what such party would be willing to pay therefor.  
The determination of Prevailing Market Rent based upon the foregoing criteria 
shall be made by Landlord, in the good faith exercise of Landlord's business 
judgment.  Within thirty (30) days after Tenant's exercise of the Option To 
Extend, Landlord shall notify Tenant of Landlord's determination of Option 
Term Rent for the Premises.  If Landlord's determination of Prevailing Market 
Rent is greater than the Preceding Rent, and if Tenant, in Tenant's sole 
discretion, disagrees with the amount of Prevailing Market Rent determined by 
Landlord, Tenant may elect to revoke and rescind the exercise of the option 
by giving written notice thereof to Landlord within forty-five (45) days 
after notice of Landlord's determination of Prevailing Market Rent.

       (e)     This Option to Extend is personal to Cygnus and to any 
assignee of the Lease which is an Affiliate (defined below) and may not be 
used by, and shall not be transferable or assignable (voluntarily or 
involuntarily) to any other person or entity.  For purposes of this Section, 
"Affiliate" means (i) any subsidiary, affiliate or division controlled by 
Tenant; (ii) a successor corporation related to Tenant through merger, 
consolidation or non-bankruptcy reorganization; or (iii) a purchaser of 
substantially all of Tenant's assets, in each case of (i), (ii) and (iii) 
which also must satisfy the requirements described in the paragraph 
immediately following Paragraph 15(d) of the Lease.

       (f)     Upon the occurrence of any of the following events, Landlord 
shall have the option, exercisable at any time prior to commencement of the 
Option Term, to terminate all of the provisions of this Section with respect 
to the Option to Extend, with the effect of canceling and voiding any prior 
or subsequent exercise so this Option to Extend is of no force or effect:

               (i)   Tenant's failure to timely exercise the Option to Extend in
       accordance with the provisions of this Section.

               (ii)  The existence at the time Tenant exercises the Option to
Extend or at the commencement of the Option Term of any default beyond any
applicable notice and grace period.

       (g)     Without limiting the generality of any provision of the Lease, 
time shall be of the essence with respect to all of the provisions of this 
Section.

       SECTION 14.  NOTICES & ADDRESSES.  The Lease is hereby amended to 
provide that all bills, statements, consents, notices, requests, demands or 
communications which either party may desire or be required to give to the 
other shall be in writing and delivered to the other party personally or sent 
by registered or certified or express United States mail, return receipt 
requested, postage prepaid, or by reputable overnight delivery service 
addressed to Landlord or Tenant, as applicable, at the addresses set forth at 
the end of this Section.  Any item sent by registered or certified or express 
mail or by such delivery service shall be effective, respectively, upon being 
deposited in the United States mail or when deposited with such delivery 
service, as shown by the records of the mail or such service.  However, the 
time period in which a response to any such item must be given shall commence 
to run from (a) in the case of mail, the date of receipt of the item by the 
addressee thereof shown on the return receipt, or (b) in the case of such 
overnight delivery service, the date of acceptance of delivery of the item by 
an employee, officer, director or


<PAGE>

partner of the recipient party.  Rejection or other refusal to accept or the 
inability to deliver because of changed address of which no notice was given, 
as indicated by mail return receipt or advice from such courier service, 
shall be deemed to be receipt of the item sent.  Notices may also be served 
by personal service upon any officer, director or partner of Landlord or 
Tenant, and shall be effective upon such service.  If Tenant is notified of 
the identity and address of any Mortgage and/or Trust Deed Holder (as used in 
Paragraph 29(b) of the Lease), Tenant shall give, by one of the methods 
described above, such party any Notice of Default (as used in Paragraph 29(b) 
of the Lease) which Tenant gives to Landlord under the Lease.  Any party 
hereto, or any Mortgage and/or Trust Deed Holder described in the preceding 
sentence, may by notice given by one of the methods described above designate 
new addreses for notices to it. Counsel for either party may deliver notices 
on behalf of its client.  The current addresses for notices to be sent to 
Landlord and Tenant respectively pursuant to this Section are as follows:

       Notices to Landlord shall be addressed:

               Metropolitan Life Insurance Company
               c/o Seaport Centre Project Manager
               701 Chesapeake Drive
               Redwood City, CA 94063

               with copies to the following:

                      Metropolitan Life Insurance Company
                      101 Lincoln Centre Drive, Suite 600
                      Foster City, CA  94404
                      Attention:  Assistant Vice President

       Notices to Tenant shall be addressed as follows:

               Cygnus, Inc.
               400 Penobscot Drive
               Redwood City, CA 94063
               Attention:  Mr. James Grady, Senior Vice President, Human
                           Resources and Administration

       SECTION 15.  TIME OF ESSENCE.  Without limiting the generality of any 
other provision of the Lease, time is of the essence to each and every term 
and condition of this Amendment.

       SECTION 16.  BROKERS.  Tenant represents that in connection with this 
Amendment it is represented by Staubach Company ("Tenant's Broker") and, 
except for Tenant's Broker and Landlord's Broker (defined below), Tenant has 
not dealt with any real estate broker, sales person, or finder in connection 
with this Lease, and no such person initiated or participated in the 
negotiation of this Lease, or showed the Premises to Tenant.  Tenant hereby 
agrees to pay any commission to which Tenant's Broker is entitled in 
connection with this Lease and agrees that Landlord is not obligated to pay 
or fund any commission payable to Tenant's Broker.  Tenant hereby agrees to 
indemnify, protect, defend and hold Landlord harmless from and against any 
and all liabilities and claims for commissions and fees arising out of a 
breach of the foregoing representation or agreement.  Landlord represents 
that in connection with this Lease it is represented by Cornish and Carey 
("Landlord's Broker") and, except for Landlord's Broker and Tenant's Broker, 
Landlord has not dealt with any real estate broker, sales person, or finder 
in connection with this Lease, and no such person initiated or participated 
in the negotiation of this Lease. Landlord hereby agrees to pay any 
commission to which Landlord's Broker is entitled in connection with this 
Lease pursuant to Landlord's written agreement with Landlord's Broker and 
agrees that Tenant is not obligated to pay or fund any commission payable to 
Landlord's Broker.  Landlord hereby agrees to indemnify, protect, defend and 
hold Tenant harmless from and against any and all liabilities and claims for 
commissions and fees arising out of a breach of the foregoing representation 
or agreement.

<PAGE>

       SECTION 17.  ATTORNEYS' FEES.  Each party to this Amendment shall bear 
its own attorneys' fees and costs incurred in connection with the discussions 
preceding, negotiations for and documentation of this Amendment.  In the 
event any party brings any suit or other proceeding with respect to the 
subject matter or enforcement of this Amendment or the Lease, as amended, the 
prevailing party (as determined by the court, agency or other authority 
before which such suit or proceeding is commenced) shall, in addition to such 
other relief as may be awarded, be entitled to recover attorneys' fees, 
expenses and costs of investigation as actually incurred, including court 
costs, expert witness fees, costs and expenses of investigation, and all 
attorneys' fees, costs and expenses in any such suit or proceeding (including 
in any action or participation in or in connection with any case or 
proceeding under the Bankruptcy Code, 11 United States Code Sections 101 ET 
SEQ., or any successor statutes, in establishing or enforcing the right to 
indemnification, in appellate proceedings, or in connection with the 
enforcement or collection of any judgment obtained in any such suit or 
proceeding).

       SECTION 18.  EFFECT OF HEADINGS; RECITALS: EXHIBITS.  The titles or 
headings of the various parts or sections hereof are intended solely for 
convenience and are not intended and shall not be deemed to or in any way be 
used to modify, explain or place any construction upon any of the provisions 
of this Amendment.  Any and all Recitals set forth at the beginning of this 
Amendment are true and correct and constitute a part of this Amendment as if 
they had been set forth as covenants herein.  Exhibits, schedules, plats and 
riders hereto which are referred to herein are a part of this Amendment.

       SECTION 19.  FORCE AND EFFECT.  Except as modified by this Amendment, 
the terms and provisions of the Lease are hereby ratified and confirmed and 
shall remain in full force and effect.  Should any inconsistency arise 
between this Amendment and the Lease as to the specific matters which are the 
subject of this Amendment, the terms and conditions of this Amendment shall 
control.  This Amendment shall be construed to be a part of the Lease and 
shall be deemed incorporated in the Lease by this reference.

       SECTION 20.  ENTIRE AGREEMENT; AMENDMENT.  The Lease as amended by 
this Amendment constitutes the full and complete agreement and understanding 
between the parties hereto and shall supersede all prior communications, 
representations, understandings or agreements, if any, whether oral or 
written, concerning the subject matter contained in the Lease as so amended, 
and no provision of the Lease as so amended may be modified, amended, waived 
or discharged, in whole or in part, except by a written instrument executed 
by all of the parties hereto.

       SECTION 21.  AUTHORITY.  Each party represents and warrants to the 
other that it has full authority and power to enter into and perform its 
obligations under this Amendment, that the person executing this Amendment is 
fully empowered to do so, and that no consent or authorization is necessary 
from any third party.  Landlord may request that Tenant provide Landlord 
evidence of Tenant's authority.

       SECTION 22.  COUNTERPARTS.  This Amendment may be executed in 
duplicates or counterparts, or both, and such duplicates or counterparts 
together shall constitute but one original of the Amendment.  Each duplicate 
and counterpart shall be equally admissible in evidence, and each original 
shall fully bind each party who has executed it.

<PAGE>

       IN WITNESS WHEREOF, the parties hereto have executed this Amendment as 
of the date first set forth above.  

       TENANT:                CYGNUS, INC
                              a Delaware corporation

                              By: /s/ James F. Grady, Jr.
                                 ---------------------------------------------
                                     James Grady,

                                     Senior Vice President, Human Resources and
                                     Administration

                                     Date: June 9, 1998


       LANDLORD:              METROPOLITAN LIFE INSURANCE COMPANY,
                              a New York corporation

                              By: /s/ Edward J. Hayes
                                 ---------------------------------------------
                                     Edward J. Hayes

                                     Assistant Vice President

                                     Date: June 9, 1998