NF-kB is a major transcription factor that plays an essential role on the regulation of immune responses.NIK, NF-Kb-inducing kinase, is required for NF-Kb activation based on the processing of NF-kB2 p100.CHIP, C-terminus of HSC70-interacting protein, is an E3 ubiquitin-ligase collaborating with molecular chaperones HSP90 and HSC70, with a U-box domain and TPR domain.Currently we find protein interaction between NIK and CHIP, and have got some evidence supporting that CHIP could negatively regulate NIK expression.First, we did CHIP dose experiment on NIK expression, and result showed reduced NIK expression when we increased CHIP amount.Next, we finished co immunoprecipitation (co-IP) of NIK and CHIP, protein CHIP could be pull down by protein NIK.We also did reverse co-IP experiment and pulled down protein NIK with protein CHIP.Both of the immunoprecipitation experiments further illustrated the protein interaction between NIK and CHIP.Meantime, we tested two CHIP mutants, CHIP (K30A) and CHIP (H260Q).CHIP (H260Q) worked similar to CHIP (WT), however, CHIP (K30A) lost its function on NIK degradation.For the co-IP experiment, as expected, NIK could not pull down CHIP (K30A) either.Following work is cellular experiments, we plan to set up several stable cell lines overexpressing or knocking down CHIP or CHIP (K30A) to further study cellular response.