The 2004 Nonemployee Director Stock Option Plan is hereby amended by the addition of a new paragraph 4(f), as follows:

(f) On or after June 19, 2006, all options that may be granted from time to time under the Plan shall vest and become exercisable to purchase shares of Common Stock as follows: 25% one year after the date of grant, and then 25% on each of the second, third and fourth consecutive years from the date of grant on a cumulative basis, so that each option shall become fully vested and exercisable on the fourth year from the date of grant.