CDKN1A and primary biliary cholangitis: The gene product of CDKN1a (which was up-regulated with a 1.78 fold change) (p = 0.032) in expression in high- compared to low-risk PBC (Table 3), p21WAF1/Cip, is a marker of biliary senescence and has been shown to predict outcome in a number of liver diseases and to correlate with Scheuer stage (Sasaki et al., 2010).