SYP and neoplasm: For example, in response to androgen-deprivation therapy, prostate tumor cells begin to exhibit a neuroendocrine phenotype and express neuroendocrine markers, such as Synaptophysin (SYP)5 and Chromogranin A6 (ChgA), and the degree of prostate tumor cells with neuroendocrine differentiation features correlates with tumor progression and poor prognosis in patients7, 8.