Researchers at Senesco discovered that the lysine form of factor 5A is proapoptotic, whereas the hypusine form of the protein inhibits proinflammatory cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), gamma interferon, TNF-alpha, and the transcription factor NF-kB. Several new drugs on the market target these proinflammatory cytokines.