RAD18 and rectal cancer: Apoptosis is a physiological process of endogenous programmed cell death, mediated by varieties of stimulus including chemoradiotherapy.29 5‐Fu and irradiation may exert their anticancer effects through activating cell apoptosis signaling.30, 31, 32 The prevention of apoptosis has been reported to be an important cause in chemoradiation resistance.33, 34 We have shown that inhibited RAD18 promoted the sensitivity of 5‐Fu and irradiation in rectal cancers.