Signal transduction associated with apoptotic induction and effect of caspase inhibition in the antitumor effect of celecoxib or E7123 on DLBCL cell lines. (A) Immunoblot analyses of DB, HT, and KARPAS-422 cells treated with vehicle (V), 60μM celecoxib, or E7123 for different time periods (4, 8, 15, and 24 hours). Equal loading was checked by immunobotting with GAPDH. Expression levels of Mcl-1 in DB cells and Bcl- 2 in HT cells are not shown because they were undetectable. (B) Antitumor effect of 60μM celecoxib (CX) or 30μM E7123 after 4-hour exposure in DB, HT, and KARPAS-422 cells pretreated for 1 hour with the pancaspase inhibitor ZVAD at 50μM. Error bars represent SE. Statistical analysis was performed using the Mann-Whitney test: *P < .05.