CHEK1 and hepatocellular carcinoma: Moreover, the activity of Caspase‐3, also an important apoptotic target gene of p53 28, 29, was found to be significantly increased in Mus81‐suppressed HepG2 cells under EPI treatment and this increase could be turned down by CHK1 inhibitor, suggesting a pivotal role of CHK1/p53/Bax/Caspase‐3 pathway in apoptosis of Mus81‐suppressed HCC cells in response to EPI 30.