PIGF and neoplasm: Tumor cell deprivation of oxygen induces HIF1α which dimerizes with HIF1β and translocates to a nucleus where transcription regulates expression of genes, such as VEGF, PDGF, bFGF, erythropoietin, angiopoietin, and placental growth factor (PIGF) which increase cell proliferation, metabolism, and abnormal tumor blood vessels [53].