AKT1 and neoplasm: Low concentrations of NO (range, 1–30 nM) produced high levels of cyclic guanosine monophosphate, promoting tumor angiogenesis and the proliferation of endothelial cells, and a wider range of NO concentrations (range, 0–100 nM) corresponded to an increase in the activity of the proliferative and anti-apoptotic Akt and Erk-dependent pathways in tumor cells (35,36), appearing to enhance angiogenesis and protect tumor cells from apoptosis.