CHEK1 and hepatocellular carcinoma: Following treatment of HCC with 20 mU/ml BLM for different time points, as results shown in Figure 1B, both levels of phosphoserine 139-(γ)-H2AX and phosphorylated Chk1 at serine 345 (pS345), the commonly used DNA damage markers [33], [34], were increased in a BLM-inducible and time-dependent manner and were reached to activation peak at 2h time point.