EXHIBIT 10.21 EMPLOYMENT AGREEMENT  This EMPLOYMENT
AGREEMENT, dated as of May 15, 2000 between BIONEBRASKA, INC., a corporation
incorporated and existing under the laws of Delaware and having its office at
3820 NW 46th Street in Lincoln, Nebraska (hereinafter referred to as
"Company"), and DAVID S. WALKER,
residing currently at 150 Riverview Road, Glastonbury, Connecticut 06033  (hereinafter referred to as the
"Executive"). WHEREAS the Company
desires to employ the Executive as its Senior Vice President and Chief
Financial Officer and, as such, as a member of its management group; and the
Executive desires to be so employed: NOW THEREFORE, in
consideration of the foregoing and of the mutual promises hereinafter set
forth, the parties hereto agree as follows: 1.       Employment: Powers and Duties. The Company hereby
employs the Executive as its Senior Vice President and Chief Financial Officer,
pursuant to the provisions of this Agreement. 
The Executive shall generally have the responsibilities, duties and functions
as set forth in Annex A attached.  The
Executive shall perform services in such capacity for the Company and for any
of its affiliates or subsidiaries with such authority and with such powers and
duties as may be prescribed or assigned to him from time to time by the Board
of Directors of the Company and by the Chairman of the Board and the
C.E.O.  In performing his services
hereunder, he shall report to the Chairman of the Board and C.E.O. and consult
with the President, particularly on matters affecting the science of the
Company. 2.       Exclusivity. During the term of
his employment hereunder, the Executive will devote his best efforts, energy,
skill and resources to his duties hereunder and to the affairs and interests of
the Company and its affiliates, joint ventures and subsidiaries and will not,
without the approval of the Board of Directors of the Company or the Chairman
of the Board and C.E.O., actively engage in consulting for, or in the conduct
of, any other business for profit. 3.       Direct Compensation During his employment hereunder, the Executive shall
receive salary at the annual rate of two hundred twenty thousand dollars
($220,000).  This compensation will be
paid in equal monthly installments. All required tax and other deductions will
be made from such installments.  At the end of each calendar year under this Agreement, the
performance of the Executive will be reviewed. 
In the event that his performance and contributions to the Company have
been in accordance with or exceeding expectations for the particular calendar
year, it is anticipated that, assuming the Company's situation permits, the
Executive will receive a positive adjustment to his salary level over that
obtained in the previous year.

In addition,
assuming the Company's situation permits, the Board of Directors of the Company
or the CEO (in their sole discretion) may establish for any calendar year an
appropriate incentive or bonus program which can provide to individual members
of the management group of the Company, including the Executive, additional
incentive compensation in the event that certain goals, to be mutually agreed
upon by the Company and each group member, are met or that substantial business
contributions, not in the ordinary course of his or her duties, are made by the
Executive or other members of the management group to the business of the
Company during the calendar year.

4.       Additional Benefits.

(A)     The Executive shall be provided with such
health and sickness, accident, hospitalization, disability, life and other
insurance benefits as are generally provided under the Company's and/or its
affiliates' group policies. This will include life insurance coverage of at
least $100,000 for the Executive.

(B)     When
and if instituted, the Executive shall be provided with such savings and
retirement plan benefits as may be provided in general for employees under the
Company's plans, as adopted or amended from time to time, based on his
compensation received from the Company from time to time.  The Company has established a 401(K) Plan
for retirement savings for all employees. 
Initial Company contributions to this Plan are expected to be small or
non-existent until funding or profits of the Company permit (as determined in
the sole discretion of the Board of Directors) one or more of such
contributions from time to time.

5.       Long-Term Stock Option Incentives.

The Executive shall be allotted an incentive stock option under the
Company's 1993 Stock Plan, as amended, covering a total of fifty thousand
(50,000) shares of the Company's Common Stock. 
This option will be vested and become exercisable thereafter in three
equal annual installments over the three years, beginning as of the date which
is one year after the date of this Agreement. 
The option price will be $12.50 per share, being the fair market value
of the shares at the time the options are granted, as determined by the Board
of Directors.

The Executive will
be eligible for one or more additional participations under stock plans of the
Company if and to the extent that the Chairman of the Board and C.E.O. or the
Board of Directors at the relevant time, in their respective sole discretion,
shall consider that the work and contributions of the Executive merit such
participation.

6.       Expenses.

The Company shall
reimburse to the Executive all reasonable travel, hotel, entertainment and
other out-of-pocket expenses which he may from time to time incur in the course
of carrying out his duties for the Company and any of its affiliates, joint
ventures or subsidiaries.

The Company shall
reimburse the Executive's reasonable costs of moving his household to Lincoln
from his current location in Connecticut. 
The Company will also reimburse the reasonable costs for the Executive
and/or his wife to make one or more trips to Lincoln from Connecticut to locate
housing.

7.       Non-Competition.

(A)     During the term of his employment
hereunder, and for a two-year period thereafter but only in the event that the
Company shall in its sole discretion continue to pay compensation to the Executive
after termination of his employment at a rate per month equal to at least one
half of the monthly salary rate enjoyed by the Executive prior to the
termination of his employment hereunder, the Executive agrees that, unless he
obtains written consent from the Company covering a particular planned
competitive activity, the Executive shall not directly or indirectly engage in,
consult for, be employed by or finance any business activity that is
competitive with the businesses which are being conducted or are planned to be
conducted by the Company or by any affiliate, joint venture or subsidiary or
client or customer of the Company at the particular time. The foregoing
notwithstanding, the Company shall have no obligation, in the event of his
termination of employment for any reason, to pay any continuing compensation
under this Section 7 to the Executive or, in the event such continuing
compensation is paid for one or more months, to continue to pay such
compensation. In the event any such continuing compensation is not paid, or is
terminated after one or more monthly payments, the foregoing restrictions on
competitive activity shall not apply thereafter.

(B)     In no event without receiving the Company's
prior written consent will the Executive, at any time during his employment
hereunder or within a period which is two years after termination for any
reason of his employment hereunder:

(i)
  preempt, divert, disrupt or otherwise interfere with any business
  relationship of the Company, or of any of its affiliates, joint ventures or
  subsidiaries, with any of the clients, customers or business contacts of the
  Company or of any of its affiliates, joint ventures or subsidiaries; or(ii)
  employ or solicit for employment for his own or another's benefit, as
  employee, partner, consultant, independent contractor or otherwise, or
  directly or indirectly suggest to others to employ or to solicit for
  employment, any person who is at the time employed by the Company or by any
  affiliate, joint venture, subsidiary, client or customer of the Company.



8.       Intellectual Property Rights.

(A)As between the Company or any of its
affiliates, joint ventures or subsidiaries, as the case may be, and the
Executive, all products, know-how, methods, processes, discoveries, materials,
ideas, strategies, creations, inventions, medical or clinical ideas, results or
innovations and properties pertaining or relating to the businesses of the
Company, or of any affiliate, joint venture or subsidiary of the Company, which
the Executive may create by himself or with others or to which he may become
exposed, whether or not developed or invented by the Executive and whether or
not developed or discovered during regular working hours, shall be the sole and
absolute property of the Company or the particular affiliate, joint venture or
subsidiary, for any and all purposes. 
The Executive shall not claim to have, under this Agreement or
otherwise, any right, title or interest of any kind or nature in any of the
foregoing.

(B)     The Executive acknowledges that in the
course of his employment hereunder he will make use of, be exposed to, acquire
and add to Confidential Information of the Company and its affiliates, joint
ventures and subsidiaries as well as of its customers, clients and other
persons and entities having a business relationship with the Company, relating
to such matters as trade secrets, products, technical systems, processes and
procedures, clinical ideas, results or innovations, know-how, inventions,
manuals, confidential reports, plans, properties, strategies and customer or
investors business (referred to as Confidential Information); and that such
Confidential Information will have a special and unique nature and value.  The Executive agrees that with respect to
any and all of the foregoing Confidential Information, during and following the
term hereof, and for so long as same remains confidential (and beyond this time
should loss of confidentiality be caused directly or indirectly by the
Executive), he will not, for any purpose (unless otherwise agreed to by the
Company in writing), divulge, disclose, use or otherwise exploit any of such
Confidential Information or let or suffer others to use or otherwise exploit
such Confidential Information for any purpose other than for the benefit of the
Company or its affiliates, joint ventures or subsidiaries, as the case may be.

9.       Term of Employment.

The Executive's
employment shall continue indefinitely hereunder, unless and until terminated
by either party upon delivery of six months' prior written notice of
termination to the other party.

Notwithstanding the
foregoing, the Company shall be entitled by notice in writing to the Executive
to terminate forthwith his employment with the Company under this Agreement if
he shall have engaged in any willful misconduct or misconduct involving
negligence or commit any material breach of his obligations or duties to the
Company or the Companys employees hereunder.

10.     Vacation.

The Executive shall
be entitled to four weeks of vacation in each calendar year.

11.     Return of Documents in Hard Copy or
Electronically Stored.

The Executive shall promptly, upon the termination of
his employment with the Company hereunder, deliver and transfer over to the
Company all copies, both in hard copy and electronically created and/or stored, of reports, memoranda, accounts, laboratory,
clinical and other notebooks, records, correspondence and e-mail (Company
Documents) which may have been prepared by him or have come into his
possession or control in the course of his employment and the discharge of his
duties hereunder.  Unless otherwise
agreed to in writing by the Company or unless the particular item has been
published in the public domain, the Executive shall not retain any of copies of
Company Documents, either in the form of hard copy or in electronically stored
form.

12.     Notices.

All notices
hereunder shall be in writing and delivered personally or by registered or
certified mail which shall be addressed to the Company at its principal office,
marked to the attention of the Chairman of the Board and C.E.O. and to the
Executive at the address stated in the first paragraph of this Agreement, or in
either case at such other address as shall have previously designated in
writing by the party to whom the notice is to be sent to the other party.  Any such communication so sent by mail shall
be deemed made or given upon mailing.

13.     Miscellaneous.

The BioNebraska
Employee Handbook (the Handbook) has been furnished to the Executive and
shall form part of this Agreement.  The
Executive agrees to comply with operational rules of the Company as adopted
from time to time and set forth in the 
Handbook.  This Agreement
constitutes the entire agreement of the parties hereto relating to the subject
matter hereof and there are no written or oral terms or representations made by
either party relative to the subject matter hereof other than those contained
herein.  All of the terms and provisions
of this Agreement shall be binding upon, and shall inure to the benefit of and
be enforceable by and against, the parties to this Agreement and their
respective heirs, executors, and successors in interest.  The provisions of Sections 7, 8, 11, 13 and
14 hereunder shall survive the termination of this Agreement to the extent
necessary to accomplish the purposes of the provisions in such Sections.

14.     Governing Law.

This Agreement
shall be governed by, and construed in accordance with, the laws of Nebraska.

IN WITNESS WHEREOF,
the Company has caused this Agreement to be executed by its duly authorized
officer and the Executive has executed this Agreement, as of the date first
written above.

BIONEBRASKA, INC.By
  /s/  Thomas R. CoolidgeThomas R. CoolidgeChairman of the Board and C.E.O./s/  David S. WalkerDAVID S. WALKER(the Executive)


BIONEBRASKA, INC. ANNEX A  CHIEF FINANCIAL
OFFICER  The
CFO of BioNebraska will have responsibility for implementing and monitoring all
financial activities of the Company. These activities will include
disbursements, appropriate record keeping, report and financial statement
preparations, budgeting and expenditure tracking and continuous attention to
expenditure savings in all activities of the Company. The CFO will be
responsible for liaison with the Companys independent accountants and, where
appropriate, will be the Companys spokesman on financial and related matters
with stockholders, potential investors and the financial media. The CFO will
periodically prepare appropriate financial projections for the Company and its
key medical and other programs, will assist the CEO in developing, maintaining
and updating the Companys business plan. He will be responsible for the
preparation and integration of operating budgets for the Company and its
various departments as well as capital budgets for facilities construction and
other activities. He will also track compliance with budgets. He will assist
the officers of the Company in designing and implementing systems for budgeting
and tracking budgeted operations, as well as capital project activities,
expenditures and implementations. The CFO will have such other responsibilities
as may be assigned to him by the CEO or the Board of Directors and will report
to the CEO.