GRP and neuroendocrine neoplasm: Surprisingly, a large proportion of the published models (∼70%) express markers that are typically found in neuroendocrine tumors (Table S5, Supporting References S1), like peptide hormones (gastrin, gastrin-releasing peptide, somatostatin, glucagon), proteins stored in specific secretory granules (chromogranin A and B, synaptophysin) and neuroamines (serotonin, dopamine).