We have recently attempted to study the mechanisms by which small cell lung cancer (SCLC) arises in human lung cells by efficiently differentiating human embryonic stem cells (hESCs) (Huang et al., 2015; Huang et al., 2014) into mature lung epithelial cells, including the likely precursor of SCLC (pulmonary neuroendocrine cells [PNECs]) and then simulating loss of function of the tumor suppressor genes TP53 and RB1, tumor suppressors commonly lost in human SCLC (Chen et al., 2019). The gene discussed is RB1; the disease is neoplasm.