MMP9 and neoplasm: To investigate the possible mechanisms involved in the metastatic progression of H1299 cells, we examined the MMP-2 and MMP-9 protein levels after treatment with PI3K/pAkt and MAPK/pERK1/2 inhibitors (LY294002 and PD98059), and the reduced expression of the MMPs confirmed the indispensable role of pAkt and pERK1/2 in radiation-induced tumor invasion and metastasis.