ASCL1 and NEUROD1, along with insulinoma-associated protein 1 (INSM1) and POU class 3 homeobox 2 (BRN2), are recognized as important master regulators for NE differentiation in SCLC (Rudin et al., 2019; Fujino et al., 2015; Ishii et al., 2013). Here, NEUROD1 is linked to small cell lung carcinoma.