Retention of p63 in an ER-Golgi intermediate compartment depends on the presence of all three of its domains and on its ability to form oligomers

cos cells were grown in eight-well multichamber slides. The immunofluorescence procedure for permeabilized cells was that of Schweizer et al. (1988) . In brief, formaldehyde-fixed and sapenin-permeabilized cells were incubated with mAb G1/296 against p63 or rnAb HBB 3/775 against DPPIV followed by goat anti-mouse FITC. To probe for surface expression of proteins, COS cells were cooled to 4°C for 20 rain and kept on ice for the subsequent steps. The cells were washed once with PBS-0.2% BSA, and incubated with mAb G1/296 or mAb HBB 3/775 for 45 rain. After six wash steps with PBS-0.2% BSA, the cells were fixed with 3% p-formaldehyde for 30 rain on ice, followed by another 30 rain at room temperature. Cell permeabilization and staining with goat anti-mouse FITC was as described (Schweizer et ai., 1988) . The specimens were examined with a Nikon fluorescence microscope and photographed with 1600 Fujichrome film.