Slp2a-hem and Rab27a colocalize on the same vesicular structures, and the latter is distinct from perforin-containing granules. (A) Confocal microscopy of wild-type LAK-T cells transfected with GFP-Slp2a-hem and stained with a perforin monoclonal antibody (red). (B) Confocal microscopy of wild-type LAK-T cells transfected with GFP-Slp2a-hem and DsRed-Rab27a. (C) Confocal microscopy of wild-type LAK-T cells transfected with either GFP-Slp2a-hem and unlabeled Rab27a (top panel) or GFP-Rab27a and unlabeled Slp2a-hem (bottom panel). Fixed cells were then stained with an antiperforin (red). (D) Confocal microscopy of GS2 (Rab27a-deficient) LAK-T cells transfected with GFP-Slp2a-hem and labeled with an antiperforin (red) (top panel). Confocal microscopy of GS2 LAK-T cells cotransfected with GFP-Slp2a-hem and DsRed-Rab27a (bottom panel). Scale bars represent 5 μm. Data are representative of at least 4 independent experiments.