YY1 and hepatocellular carcinoma: Further, western blot analyzed the levels of proteins associated with apoptosis (Bcl-2 and Bax) and cell cycle (cyclin D1 and CDK4), delineating the reduced Bcl-2, cyclin D1 and CDK4 levels and increased Bax level in HCC cells in response to YY1 suppression (Fig. 1h and Additional file 2: Fig. S1B).