Therefore, the cancer-associated hypoxic conditions up-regulate Hypoxia-Inducible Factor (HIF)-1α transcription factor to increase its target genes, which include vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), placental growth factor (PlGF), and hepatocyte growth factor (HFG) in tumors to generate angiogenic tumor vessels (62–65). Here, PGF is linked to cancer.