ASCL1 and small cell lung carcinoma: The characteristics of SCLC cells are thought to depend on the expression of several neuroendocrine-related genes, including the achaete-scute family basic helix-loop-helix transcription factor 1 (ASCL1, also known as ASH1), synaptophysin (SYP), neural cell adhesion molecule (NCAM) and v-myc avian myelocytomatosis viral oncogene lung carcinoma derived homolog (MYCL) [19].