PGF and melanoma: In addition to VEGFs, other growth factors, cytokines, and integrins, including basic fibroblast growth factor (bFGF), placental growth factor (PGF), urokinase plasminogen activator [30], IL8, αvβ3 and αvβ5 integrins, and angiopoietins play important roles in melanoma angiogenesis [25].