Knock down of HIF-1α reduces hypoxia-induced HIF-1α expression and hypoxia-induced migration of glioma cells. (A) Western blot showing the expression level of HIF-1α under normoxic (Norm) and hypoxic (Hyp) conditions in human (LN308 and U87MG), and murine (GL261) glioma cell lines, after HIF-1α shRNA lentivirus-mediated infection (shHIF). β-Actin was used as loading control. A representative result of two independent experiments is shown. (B) Knock down of HIF-1α reduces hypoxia-induced migration of glioma cells. Boyden chamber assays showing migration of human (LN308 and U87MG) and murine (GL261) glioma cell lines infected with HIF-1 shRNA (shHIF) or the control cells. Two independent experiments, done in duplicate, were performed. Each graph represents the number of cells per field counted after 16 h of migration in either a normoxic (Norm) or a hypoxic (Hyp) environment (three asterisks, p < 0.0001).