H2BY37ph is involved in Wee1‐mediated H2BK120ub through interaction with the E3 ubiquitin ligase RNF20‐RNF40 complex and upregulates its phosphorylation, mutation of H2BY37 phosphorylation sites attenuated DSB repair and enhanced the sensitivity of IR‐induced SCLC cell death. The gene discussed is RNF40; the disease is small cell lung carcinoma.