Cells were fixed in 4% paraformaldehyde and then permeabilized with 0.25% Triton X-100 in PBS. Cells were blocked in PBS containing 0.25% Triton X-100 and 10% donkey serum. Antibodies and quantification methods used are described in the Supplemental Experimental Procedures. Fluorescent signals were detected using a Zeiss 710 laser scanning microscope and images were processed with ZEN 2011.
