DLL1 and neoplasm: In agreement with our previous results, the PCA showed convergent expression of ASCL1 with MYCL, DLL1, -3, CDH2 and EPCAM, NEUROD1 with MYCN, and YAP1/POU2F3 with MYC, NOTCH1, -2, -3, REST, VIM, and TGFB1. Together, these analyses demonstrate heterogeneity within individual tumors, with each tumor harboring cells of more than one SCLC subtype and various developmental stages, while being driven by a dominant transcriptional program.