At the molecular level, we have: (1) identified PPP1R12B as a novel PAK2-interacting protein; and (2) revealed that PPP1R12B inhibits these processes by suppressing β-catenin expression and Ser675 phosphorylation, ultimately leading to cell cycle arrest at the G0/G1 to S phase transition in HCC cells as well as in liver normal cells. Here, PPP1R12B is linked to hepatocellular carcinoma.