MMP9 and central nervous system cancer: Adenosine is another factor engaged in progression of gliomas by activation of P1 receptors and thus induction of glioma cells proliferation [134], tumour growth, angiogenesis (A2B receptor), inhibition of immune response (inhibition of Tc lymphocytes migration and neoplastic cells recognition) (A2A) [137], increase in U138MG glioma cells adhesion [143], as well as expression of IL-6 and IL-8 (A2B) in U87MG human glioma cells and expression of MMP-9 (metaloproteinase-9) (A3) in glioblastoma multiforme cells [137].