Iris-derived melanocytes contain a growth factor that resembles basic fibroblast growth factor.

A melanocyte growth stimulating factor has been purified from bovine iris melanocytes and identified as being closely related to the basic form of fibroblast growth factor (bFGF). This conclusion was based on the behavior of the melanocyte-derived growth factor when submitted to heparin-Sepharose affinity chromatography, as well as on its ability to cross-react with bFGF in radioimmuno- and radioreceptor assays. The ability of neutralizing bFGF antibodies to block cell proliferation in response to the melanocyte growth factor further confirms that it is closely related to bFGF. Since melanocytes express the 3.7-kb and 7.0-kb bFGF transcript, the possibility exists that uncontrolled expression of melanocyte-derived bFGF could be involved in the malignant transformation of melanocytes into melanoma cells.