Both inflammation and tumorigenesis are analogous counterpart phenomena in overlap dynamics determining angiogenesis within reactive microenvironments and as angiogenic switch in tumorigenic expansion and progression. In this regard, the counter-effects of pro-angiogenesis and of anti-angiogenesis reconstitute a series of endothelial cell activation steps or apoptosis of these cells. In close parallel, apoptosis of endothelial cells in response to inhibitory angiogenic factors may reflect in some measure apoptosis of tumor cells related to such sprouting endothelial cell tubes. Further to such measures, multi-potent bone marrow mesenchymal cells induce a plethora of effects relative to the migrating endothelial progenitor cells in terms of the ongoing promotion of angiogenesis and of the angiogenic switch. Indeed, angiogenesis of tumors may prove a central modulator in emergence of malignant potentialities in tumorigenic lesions.