CDK4 and liver cancer: These results strongly suggest that H2A.Z.1 overexpression causes the suppression of the negative cell cycle modulators such as p21WAF1/Cip1 and p27Kip1 and at the same time, induces the expression of their specific regulators such as CDK4, CDK6, cyclin D1, CDK2 in the cell cycle transition of liver cancer cell.