Thus, PP4 acted as a negative regulator of RNA virus-triggered innate immunity.228 In experiment colitis, PP4 was pivotal for the maintenance of gut immunity through its positive regulation of Treg development and function.229 PP6, closely related to PP2A and PP4, has a bimetallic catalytic center and a known involvement in NF-κB signaling regulation. This evidence concerns the gene PPP4C and colitis.