A crucial role for fibroblast growth factor signaling in embryonic mammary gland development.

The fibroblast growth factors (Fgfs) represent a large group of intercellular signaling molecules that mediate their effects by binding to a class of cell surface enzymes belonging to the receptor tyrosine kinase family (FgfRs). In vitro, Fgf signaling can induce potent mitogenic, motogenic, and angiogenic cellular responses, and has been associated with a multitude of biological processes. The development of gene targeting and transgenic strategies has provided unequivocal evidence for the key involvement of Fgf signaling in mammalian developmental processes. In this review we highlight recent findings that demonstrate a critical requirement for Fgf signaling in the induction and development of the embryonic mammary gland. Furthermore, we briefly discuss the potential of Fgfs to act as oncogenic factors in mammary neoplasia.