(A) (left panel): LN229 and U87MG cells were transfected with integrin β3-, α4-, β5- or ns-siRNA, respectively, and 48 h later exposed to TMZ (100 μM). After 96, 120 and 144 h the cells were subjected to subG1 flow cytometric analysis. The data are the mean of two independent experiments in duplicates ± SD. (A) (right panel): LN229 and U87MG cells were transfected with integrin β3-, α4-, β5- or ns-siRNA, respectively, and 24 h later re-seeded in the 96-well plate. After additional 24 h cells were treated with TMZ (100 μM) and 120 h later the caspase-3/7 activity was determined. (B) LN229 and U87MG cells were pre-treated with a cyclo-RGD integrin antagonist (10 μg/mL) alone, or exposed, in addition, to TMZ (100 μM). 120 h later, the cells were subjected to annexin V/PI staining and to caspase-3/7 analysis. The data are the mean of two independent experiments in duplicates ± SD. *p ≤ 0.05 significant, **p ≤ 0.01 very significant, ***p ≤ 0.005 highly significant, ****p ≤ 0.001 most significant. n.s., not significant.