Representative Western blot study from patient 17 demonstrating findings before and after therapy with rituximab.

CLL cells from the blood were recovered from patients before treatment (−) and on days 1 and 3 of treatment (+). Protein lysates were prepared, normalized for total protein content, and analyzed by SDS-PAGE/immunoblotting using antibodies specific for casepase-3, caspase-8, caspase-9, PARP, Mcl-1, and XIAP. Mcl-1 and XIAP are down-regulated. Caspase-3 was processed with formation of active p17 after treatment with rituximab on days 1 and 3 concurrent with PARP cleavage. Caspase-8 proform level remained unchanged. Caspase-9 proform level was reduced after treatment with rituximab on days 1 and 3, indicating that caspase-9 is being processed.