ASCL1 and small cell lung carcinoma: Rubin et al. conducted a genetic study using RNA expression in SCLC cell lines derived from mice, dividing SCLC into four biological subtypes, SCLC‐A, SCLC‐N, SCLC‐P, and SCLC‐Y, based on different transcriptional regulatory factors, ASCL1, NEUROD1, POU2F3, and YAP1, respectively.