– Anterior Gradient 2 (AGR2) is an 18-21 kDa member of the PDI family of enzymes. AGR2 is widely expressed in secretory cells, such as small intestine goblet, prostate epithelium, enteroendocrine cells, and multiple carcinoma cell types. AGR2 forms transient disulfide linkages with molecules destined for secretion, possibly aiding protein folding. Expression of AGR2 shows a positive correlation with expression of estrogen receptor in breast carcinoma and a negative correlation with expression of EGF receptor. Mature human AGR2 is 155 amino acids (aa) in length (aa 21 – 175). Cys81 is presumed to participate in intermolecular bond formation. Over aa 21 – 175, human AGR2 shares 94% aa identity with mouse AGR2.