MMP9 and hepatocellular carcinoma: Studies in hepatocellular carcinoma and glioblastoma cell lines have shown that the activation of the PI3K/Akt pathway and subsequent NF-kB or mTOR activation upon radiation leads to the secretion of matrix metalloproteinases (MMP), mainly MMP-2 and MMP-9, and consequently to enhanced cell invasion [6, 10, 11].