Importantly, deletion of Rb1 and Trp53 and activation of Myc in NE cells using Ad5-CGRP-Cre were shown to result in the development of the NeuroD1 variant form of SCLC (Mollaoglu et al. 2017), indicating that different subtypes of SCLC may arise from the same cell type. Here, RB1 is linked to small cell lung carcinoma.