TP53 and cancer: In addition to Cip/Kip, zebularine can up-regulate ink4 p15INK4b and p16INK4a in colon cancer Caco-2 cell (Berner et al., 2010), and also p53 in colon cancer (Yang et al., 2013) and other cancer such as HCC (Nakamura et al., 2013).