PGF and myocardial ischemia: Though PlGF is known to stimulate cycling and differentiation of VEGFR-1+ Sca-1+lin− (SL) cells after myeloablation [29] and to recruit BM-derived endothelial progenitors to tumors [10], the effects of PlGF on marrow progenitors have generally been much less characterized – especially in conditions of myocardial ischemia.