SOX2 and small cell lung carcinoma: Additionally, as SCLCs are tumors that possess neuroendocrine features, conditional induction of SOX2 in lung epithelial cells is also known to increase the number of neural progenitor cells (Gontan et al., 2008), SOX2 protein overexpression has also been previously noted in high‐grade SCLC, and immunoreactive antibodies against SOX2 have been detected in sera from SCLC patients (Gure et al., 2000; Sholl, Long, & Hornick, 2010).