Fibroblast growth factor 8 (androgen-induced), also known as FGF8 or AIGF, is a human gene which maps to 10q24. The protein encoded by this gene are secreted proteins that interact with FGF tyrosine kinase receptors to mediate growth and development. This protein is known to be a factor that supports androgen and anchorage independent growth of mammary tumor cells. Overexpression of this gene has been shown to increase tumor growth and angiogensis. The temporal and spatial patterns of this gene expression suggest that FGF8 is involved in gastrulation, regionalization of the brain, and organogenesis of the limb and face as an embryonic epithelial factor. The adult expression of FGF8 is restricted to gonads, including testes and ovaries. FGF8 stimulated growth of human prostate carcinoma cells and mouse fibroblasts and mammary carcinoma cells in a dose-dependent manner. It also may play an important role in growth and patterning of limbs, face, and central nervous system. FGF8 is expressed in increased levels in breast cancer and in lactating human breast; it was also detected in human milk. A survey of other normal tissues showed that FGF8 is expressed in the proliferative cells of the skin and epithelial cells in colon, ovary, fallopian tube, and uterus.