PGF and osteosarcoma: Babkina et al. (2009) compare serum levels of endostatin, placental growth factor (PlGF) and fibroblast growth factor-1 and -2 (FGF-1 and FGF-2) among patients of osteosarcoma and a group of control patients; the author found increased levels of PGF-2, PIGF and endostatin, while the levels of FGF-1 are increased of 2.5 times (p = 0.004) (Babkina et al., 2009).