Imatinib inhibits the capacity of CD154 to induce CLL-cell expression of TAp73 α and Bid. (A) Cell lysates were prepared from CLL cells prior to culture (before) or at 0 (day 0), 1 (day 1), 3 (day 3), or 5 days (day 5) after 24-hour culture with HeLa-CD154 in media without (-) or with (+) 10 μM imatinib. Fifty micrograms of protein from each lysate was loaded onto separate lanes for PAGE and immunoblot analyses, as indicated at the top of each panel. Immunoblots were stained with antibodies specific for p73 (TAp73α) or β-actin (to control for protein loading), as indicated at the right of each immunoblot. (B) Immunoblots as in panel A were stained with antibodies specific for Bid or β-actin, as indicated at the right of each immunoblot.