Chromogranin A (CgA), UniProt # P10645, is a 439 amino acid member of the granin family of secretory proteins. Found in vesicles of neuroendocrine cells, CgA is considered a valuable marker for neuroendocrine tumors. CgA is a precursor to a number of biologically active peptides including vasostatin I, parastatin, and pancreastatin.