PGF and melanoma: Melanoma cells serve as the source of several classical angiogenic growth factors including but not limited to vascular endothelial growth factor (VEGF), also known as the vascular permeability factor (VPF), fibroblast growth factor (FGF), interleukin-8 (IL-8), and placental growth factor (PlGF), all potent contributors of angiogenesis (Figure 4) (85).