SOX2 and neuroendocrine neoplasm: Sholl et al. examined 121 lung tumor specimens for Sox2 protein expression by IHC and demonstrated that SOX2 is strongly and diffusely expressed (extensive SOX2 staining described as immunoreactivity in>50% of tumor cells) in approximately 90% of squamous cell cancers, 21% of adenocarcinomas, and 72% of high grade neuroendocrine tumors (68).