Protiva Dismisses, Without Prejudice, Its California Litigation Against Inex

Protiva is taking this action in order to focus its resources on pursuing its:

- motion for a preliminary injunction against Sirna Therapeutics, Inc. (NASDAQ:RNAI) in the Superior Court of the State of California; and its

- appeal to the BC Court of Appeal, which seeks to overturn a November 23rd, 2006, ruling by the BC Supreme Court that overrode Protiva's contractual right to withhold consent to transfer the Protiva-Inex Agreements.

Protiva's President and CEO, Dr. Mark Murray, said, "Inex has adopted a deliberate strategy of delay and non-cooperation with respect to producing the information required by the Court in California to establish jurisdiction. Rather than waste our time and energy fighting their tactics, we have chosen to put our California claims against Inex aside for now. We expect to come back to them at a later date."

"In the meantime, we are actively pursuing the motion we filed on December 1st for a preliminary injunction that would prohibit Sirna from, among other things, unlawfully transferring Protiva's trade secrets and know-how to Merck. We are also continuing to pursue our appeal to the BC Court of Appeal in the BC litigation against Inex. We are hopeful a hearing on that matter will be held some time in February."

About Protiva

Founded in 2001, Protiva Biotherapeutics Inc. is focused on the development of nucleic acid based pharmaceutical products to fight serious human diseases, such as cancer, influenza (including H5N1), Ebola, inflammatory diseases and other chronic viral infections. Protiva's proprietary Stable Nucleic-Acid Lipid Particle (SNALP) technology is an encapsulation and delivery system for nucleic acid payloads, such as short interfering RNA (siRNA), to target cells. It represents a breakthrough in the field of RNA interference.

Protiva is headquartered in Vancouver, B.C. with offices in Seattle, Washington.

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