Chromogranin A is a member of the chromogranin/secretogranin family of neuroendocrine secretory proteins. It is located in secretory vesicles of neurons and endocrine cells. Chromogranin A is the precursor to several functional peptides including vasostatin, pancreastatin, catestatin and parastatin. These peptides negatively modulate the neuroendocrine function of the releasing cell (autocrine) or nearby cells (paracrine). Chromogranin A might promote the generation of secretory granules. It is used as an indicator for pancreas and prostate cancer. It might play a role in early neoplasic progression. It is also elevated in diabetes.