These subtypes are defined by the relative expression of four key transcriptional regulators: ASCL1-high (SCLC-A), NEUROD1-high (SCLC-N), POU2F3-high (SCLC-P), and YAP1-high (SCLC-Y) [2]. The gene discussed is POU2F3; the disease is small cell lung carcinoma.