ATM and hepatocellular carcinoma: Therefore, the protein levels of CDT1 and ATM in HCC cells were assessed using Western blot assays, wherein the HCC cells stably expressing HBx-TM had higher CDT1 and ATM protein levels compared with the HCC cells stably expressing HBx-WT (Figures S9E and S9F), suggesting that the presence of DNA DSB in the HCC cell lines stably expressing HBx-TM.