These include cAMP-protein kinase A (PKA) and Src kinase signaling pathways, which are both involved in the adrenergic regulation of cancer cell proliferation and invasion, as well as the inhibition of VEGF receptor-2 tyrosine phosphorylation and MMP-9 secretion, which have been shown to mediate the anti-angiogenic effects of propranolol in vitro [17, 18, 42, 43]. Here, MMP9 is linked to cancer.