Ariad Pharmaceuticals et al. v. Eli Lilly and Company, 598 F.3d 1336 (Fed. Cir. 2010) (en banc), is a United States court case regarding accusations of infringement by Eli Lilly on U.S. Patent 6,410,516 held by ARIAD Pharmaceuticals. The Federal Circuit ruled en banc to invalidate the patent for a lack of sufficient description of the invention. Amici briefing before the en banc panel was intensive, with 26 separate briefs filed, and the final decision has been heavily discussed by legal commentators. Its ultimate impact on biotechnology patents remains to be determined. The '516 patent was licensed by Ariad from Massachusetts Institute of Technology (MIT), Harvard, and the Whitehead Institute. Nuclear factor-kappa B (NF-kappaB) is a transcription factor that plays a critical role in many cell functions including embryonic and neuronal development, cell proliferation, apoptosis, and immune responses to infection and inflammation. Defendant Lilly was manufacturing two drugs accused of infringing the '516 patent: Evista(r) for the treatment of osteoporosis and prevention of breast cancer, and Xigirs(r) for the treatment of sepsis. On May 4, 2006, Lilly was ordered to pay ~$65 million in back royalties, and 2.3% royalties on future sales of the drugs Evista and Xigris which inhibit NF-?B production.