We previously found that cultured neural crest-derived cells from embryonic 
quail peripheral nerves, which consist mostly of Schwann cell precursors, gave 
rise to melanocytes following treatment with basic fibroblast growth factor 
(bFGF) or 12-O-tetradecanoyl phorbol-13-acetate (TPA). Here, we show that 
antisense deoxyoligonucleotides targeted against two regions of the bFGF mRNA 
transcript blocked this TPA-induced transdifferentiation of Schwann cell 
precursors. Neither sense nor scrambled antisense control oligonucleotides had 
any effect in this regard. TPA increased bFGF protein expression in cell lysates 
but not in conditioned media from these cultures, and this expression was 
localized to the nucleus and cytoplasm. Furthermore, bFGF-neutralizing 
antibodies and inositol-hexakisphosphate (InsP6) both inhibited pigmentation 
caused by exogenous bFGF, but had no affect on TPA-induced melanogenesis, 
suggesting that bFGF is not released by these cells. These data indicate that 
bFGF is necessary for the TPA-induced transdifferentiation of Schwann cell 
precursors into melanocytes and that bFGF acts via an intracrine mechanism.