Rituximab treatment in vivo often results in favorable changes in Mcl-1 and XIAP expression.

CLL cells from the blood were recovered from patients before 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 Mcl-1 and XIAP. Protein bands were quantified by laser densitometry. Mcl-1 and XIAP are significantly (P < .05) down-regulated relative to the pretreatment expression on days 1 and 3 in the majority of patients tested.