ASCL1 and small cell lung carcinoma: Moreover, lineage‐specific transcription factors (TFs) play a crucial role in determining lineage bifurcation (Figure 3), with SCLC divided into four molecular subtypes, including ASCL1, NEUROD1, TF POU class 2 homeobox 3 (POU2F3), and YAP1, or Inflamed subtype, similar with the mutually exclusive pattern of the MYC family.12, 13