High expressions of both PDGF-B and PDGFR-β mRNA were found in the endothelial cells present in the tumor tissue; these were thought to stimulate the autocrine loop with the PDGFR-β receptor, while PDGF-A mRNA and PDGF-α were observed only in the glial tumor cells stimulating the autocrine/paracrine loop with the PDGFR-α receptor [73]. This evidence concerns the gene PDGFA and neoplasm.