Cancer cell lines A549, HepG2, and HCT116 revealed high degree of ALDH1L1 promoter methylation, and treatment of FDH-deficient A549 cells with the methyltransferase inhibitor 5-aza-2′-deoxycytidine restored FDH expression (Oleinik et al., 2011). This evidence concerns the gene ALDH1L1 and cancer.