TP53 and small cell lung carcinoma: Whereas this specific study demonstrated that the paracrine effect of FGF2 produced by the nonneuroendocrine tumor cells on neuroendocrine SCLC resulted in the up-regulation of the ETS transcription factor PEA3, shown to be responsible for most of the effect of paracrine signaling, we also demonstrated that Notch signaling from neuroendocrine to nonneuroendocrine cells is an inherent feature seen in their SCLC model based on inactivation of Rb1, Trp53, and Rbl2 (Lim et al. 2017).