“…TGF-a is a single chain polypeptide, related to epidermal growth factor (EGF) (Marquaradt et al, 1984;Derynck et al, 1984), able to stimulate growth by binding to and activating the epidermal growth factor receptor (EGFR) Massague, 1983a). TGF-a was originally described in the culture medium of retrovirally transformed fibroblasts (De Larco & Todaro, 1978;Ozanne et al, 1980: Roberts et al, 1980, and was subsequently detected in a number of squamous cell carcinoma (SCC) lines . This molecule has also been shown to be produced by a variety of normal sources including cells of the bovine anterior pituitary gland (Samsoondar et al, 1986), cultured human keratinocytes, skin (Coffey et al, 1987) and the maternal decidua during embryonic development (Han et al, 1987).…”