For confocal laser-scanning microscopy (CLSM) analysis, COS-1 were transfected using the Arrest-IN TM (Biosystems) reagent, according to the manufacturer's recommendations. At 24 h posttransfection, cells were fixed with 4% paraformaldehyde. Cells were imaged using a Leica TCS-SP2 confocal microscope equipped with a 636 oil immersion objective.