| NFiB-Inducing Kinase (NIK) The NFiB transcription factor can be activated by several cytokines including TNF and IL-1. The TNF receptor activates NFiB through the Traf2 adapter protein , whereas the IL-1 receptor activates NFiB in a pathway involving Traf6 . Both Traf2 and Traf6 have been shown to interact with a serine/threonine kinase designated NFkB inducing kinase (NIK), which appears to participate in the NFiB signaling cascades triggered by both TNF and IL-1. NIK associates with, and is a costimulator for IkB kinase i (IKKi). IKKi , in turn, phosphorylates IiB, resulting in I i B degradation and NF i B activation. NIK has sequence similarity to several kinases that participate in MAP kinase cascades. |