GCLC and malignant colon neoplasm: Here, by using qRT-PCR analysis on a pair of isogenic colon cancer cell lines, the HCT116 cells harboring mutant KRAS with wild-type p53 (called HCT116+/+) or p53 deletion (HCT116−/−), we found that the expression levels of CYBA, GCLC, and GCLM significantly increased in HCT116−/− cells compared to that in HCT116+/+ cells8,10 (Fig. 3a–c).