The enhanced chemical hypoxia-induced proliferation and migration observed in Ptn−/− compared with Ptn+/+ LMVECs agrees with the notion that PTN may act as an endogenous brake for the stimulatory effect of hypoxia in endothelial cells, a hypothesis verified in prostate cancer LNCaP cells with a down-regulated PTN expression. Here, PTN is linked to Familial prostate cancer.