PGF and cancer: In fact, not only cancer cells secrete high amount of VEGF and can contribute to VEGF-independent angiogenesis (by liberating various pro-angiogenic molecules, such as placental growth factor (PlGF), VEGF-C, VEGF-D, and platelet-derived growth factor (PDGF)-C) but they can also respond in an autocrine or paracrine manner to prosurvival and prometastatic VEGF signaling5.