AKAP450 knockdown impairs the activation of T-cell signaling molecules. J77/SEE-pulsed Raji cell conjugates (A) and CH7C17/HOM-2 conjugates (B) expressing control siRNA (siNeg) or AKAP450 siRNA (siAKAP). Control and AKAP450 knockdown T cells were conjugated as in Figure 3D. Cell proteins were separated by SDS-PAGE and processed for Western blotting. Blots show the phosphorylation of specific sites on Vav1 (Y174), LAT (Y191), and CD3ζ (Y83) together with the total expression of these proteins. Arrows indicate target band sizes. Graphs correspond to the densitometric analysis of the Western blots in panels A and B. One of 4 experiments is shown.