Pattern of expression of bcl-2 family members in human tonsillar B-cell populations (A) and FL cells (B). Samples from (A) FACS-sorted CD38⁻IgD⁺ naive B cells, CD38⁺IgD⁻ GC B cells, and CD38⁻IgD⁻ memory B cells and (B) samples from highly purified FL cells of five representative patients were lysed and analyzed by SDS-PAGE and Western blotting using: anti–mcl-1 polyclonal antiserum (first panel); anti–bcl-x polyclonal antiserum (second panel); anti–bcl-2 MoAb (third panel); anti–bax polyclonal antiserum (fourth panel); or anti-bad MoAb (fifth panel). Expression of the different proteins was quantitated in each lane using a Scanner phosphoimager (Alpha Innotech Corp, San Leonardo, CA). Jurkat cell line (last lane in A and B), grown in log phase, was used as control. A total of 3 × 10⁶ cell equivalents were used per test. Similar results were obtained when experiments were performed on tonsils or FL cells using an equivalent amount of protein per lane.