To clarify whether tumor‐infiltrating cytotoxic CD8+ T‐cell reduction in KRAS mutant CRC tissue was a consequence of KRAS mutation, the wild‐type Kras‐expressing MC38 cell line was stably transfected with cDNA encoding the KrasG12C to generate the cells expressing KrasG12C (designated as MC38K), while MC38 cells with transfection of the corresponding empty vectors were used as controls (MC38 hereafter). The gene discussed is KRAS; the disease is neoplasm.