Effects of tocotrienols on Bid protein activities of A549 and U87MG cells. (A) Alpha-, (B) gamma- and (C) delta-tocotrienols are able to induce higher Bid protein levels on treated A549 and U87MG cells at IC50 and ICmax concentrations for 4 h than the basal levels of untreated cells. However, 50 μM of caspase-8 inhibitor, z-IETD-fmk is able to suppress the augmentation effects of tocotrienols on Bid protein activities. *Significance levels (*p < 0.05; **p < 0.01; ***p < 0.001) are set to compare between samples. α-T3: alpha-tocotrienol; γ-T3: gamma-tocotrienol; δ-T3: delta-tocotrienol.