ASCL1 and carcinoid tumor: Carcinoid tumors have been divided into three major molecular subtypes [5], [8]: “cluster A1” is defined by DLL3 and ASCL1 expression, “cluster A2” manifests with SLIT/ROBO pathway downregulation, and “cluster B” is comprised mainly of atypical carcinoids and tumors with MEN1 mutations which display poorer outcomes [5].