The cell clones, in which the endogenous APE1 protein is co-expressed with an ectopic Flag-tagged recombinant APE1 protein, represent an overexpression model to test the role of functional and non-functional APE1 proteins in lipid-induced cytotoxic effect and mimics the condition found in advanced stages of liver cancer progression (Fig. 1A) [14]. This evidence concerns the gene APEX1 and liver cancer.