Amphiregulin is a trans-membrane protein whose protease mediated digestion of the extracellular domain enables release of mature AR. Amphiregulin works to stimulate the proliferation of some animal keratinocyles, epithelial cells and fibroblasts. It has been shown that the mRNA expression of amphiregulin can be detected in numerous carcinoma cell lines and the epithelial cells of various human tissues, including colon, stomach, breast, ovary and kidney.