Mechanistic analysis revealed lactic acid derived from mutant KRAS‐expressing tumor cells sensitized tumor‐specific cytotoxic CD8+ T‐cells to activation‐induced cell death via NF‐κB inactivation; this may underlie the inverse association between intratumoral cytotoxic CD8+ T‐cells and KRAS mutation. This evidence concerns the gene NFKB1 and neoplasm.