PECAM1 and neoplasm: The observation that mouse PlGF staining was exclusively associated with low CD31 positive staining, a characteristic of lymphatic endothelial cells (LECs), allowed us to investigate whether hypoxia could activate the expression of PlGF in LECs in vitro, and in lymphatic vessels in vivo, by analyzing two pathological angiogenic models, tumor growth and hind limb ischemia and wound healing [30].