TCL1 and AKT are recruited to membrane complexes following TCR engagement. (A) Laser confocal microscopy on unstimulated primary T-PLL cultures showed a predominantly cytoplasmic distribution of TCL1 and AKT without apparent colocalization (ctr, top panel); only rare “activated” cells show TCL1-AKT colocalization. TCR engagement using anti-CD3/28 precoated plates leads to rapid focal recruitment along with colocalization of TCL1 and AKT in a uniform perimembraneous pattern (middle panel), which was also seen with ConA/IL2 stimulation (bottom panel). (B) Continuous TCR engagement in sTCR⁺/sCD3⁺ T-PLL shifted localization of TCL1 to discrete membrane complexes that also included pAKT-S473 and LCK. Staining was done using anti-TCL1 (FITC: green) in combination with anti-AKT1/2 or anti-LCK (Cy3: red), or a TCL1 antiserum (Cy3: red) with a monoclonal anti–pAKT-S473 (FITC: green). Merged pictures are shown for low-power fields; asterisk indicates location of cell shown in enlarged panels for individual fluorochromes and merged image.