ASCL1 and small cell lung carcinoma: Recent transcriptomic advances have enabled the stratification of SCLC into four distinct subtypes, each defined by the expression of transcription factors including ASCL1 (SCLC‐A), NEUROD1 (SCLC‐N), POU2F3 (SCLC‐P), and YAP1 (SCLC‐Y) [47].