PTPRG and neuroendocrine neoplasm: As an example, strong PTPRG expression has been reported in endocrine cells of the gastrointestinal tract, pancreatic islets of Langerhans, adrenal medulla and thyroid, only associative evidence indicate a potential role in normal cell homeostasis/differentiation in this site (Brenachot et al., 2017) and that a dysregulated PTPRG could be involved the development of neuroendocrine tumors (Vezzalini et al., 2007).