CHEK2 and hepatocellular carcinoma: Cytotoxicity (MTT test), genotoxicity (alkaline comet test), and expression of Chk2 as well as FANCD2 phosphorylation and expression profiles (cell-based ELISA) were determined in human lung adenocarcinoma A549 cells and hepatocellular carcinoma HepG2 cells upon 24 h exposure to single and combined STC and 5-M-STC.