Expression levels of Bcl-xL protein in mice suffering from B-ALL. Protein lysates from (A) bone marrow (wild-type, lanes 1 and 2; B-ALL, lanes 3-5) and (B) spleen (wild-type, lanes 1-3; B-ALL mice, 4-6) from B-ALL mice were compared with wild-type littermate controls after immunoblotting with Bcl-x–, Bcl-2–, and actin-specific antibodies. Expression of p210 BCR/ABL was detected with an antibody against c-abl that also recognizes the fusion protein. Vertical bars indicate repositioned lanes.