The fact that forskolin (an activator of adenylate cyclase that increases cytosolic cAMP and PKA activity) can mimic some effects of irradiation on apoptosis or ICAM-1 overexpression suggests that phosphorylation by PKA may occur in the pathways triggered by irradiation, leading to endothelial dysfunctions [39]. This evidence concerns the gene ICAM1 and endothelial dysfunction.