Human Chromogranin A (CHGA) an acidic protein and a member of the chromogranin/secretogranin family of neuroendocrine secretory proteins. It is located in secretory vesicles of neurons and endocrine cells such as islet beta cell secretory granules in pancreas. Chromogranin A expression has been oberserved in neuroendocrine tumors, medullary thyroid carcinoma, as well as carcinoid tumors.