The MEK/ERK and Akt pathways induce distinct antiapoptotic proteins in CLL B cells. (A) Immunoblotting analysis of Mcl-1, Bcl-xL, XIAP, Bcl-2, Bim, and Bax in CLL B cells collected 48 hours after transfection with empty pcDNA3 vector (Control), myr.Akt, or CA MEK2. Actin was used as a loading control. A total of 2 representative CLL B-cell samples are shown. (B) Summary of changes in Mcl-1, Bcl-xL, and XIAP protein levels 48 hours after nucleofection with myr.Akt or CA MEK2. For quantification, band intensities were first normalized to the respective actin signal and then calculated as fold change relative to the control nucleofection, which was set to 1.0. The individual responses of the patients are shown as ○. ● represents means of 21 different experiments for Mcl-1, 13 experiments for Bcl-xL, and 18 experiments for XIAP. Error bars indicate standard deviation. P values indicate the significance of the change in expression with respect to cells transfected with the control vector.