PDGFD and melanoma: A careful examination of genes of melanoma pathway that were differentially expressed between brain regions revealed several growth factors, such as platelet-derived growth factor (Pdgfd) and fibroblast growth factors (Fgf1, Fgf16, Fgf18, and Fgf22), which suggested that these growth factors are involved in both brain function and tumor growth, although further studies are needed to illuminate the details.