Fig. 3. (A) Δ264 CFTR and F508-del are localized to the ER. CFBE41o- parental cells were plated on coverslips and co-transfected with Δ264 CFTR-mCherry (red, Δ264 CFTR) and F508-del CFTR-GFP (green, F508-del). At 48 h post-transfection, the cells were fixed, permeabilized, and stained with DAPI (blue, nucleus) and antibodies against KDEL (purple, ER). Close association or co-localization is indicated by a yellow signal. Co-transfection of F508-del CFTR-GFP and Δ264 CFTR-mCherry occurred in 21.1% of the cells (27/128); of the cells stained for KDEL (purple), 100% (11/11) showed co-localization or close association between Δ264 CFTR and F508-del. (B) Localization of Δ27-264 CFTR and F508-DEL CFTR in the ER. CFBE41o- parental cells were plated on coverslips and co-transfected with Δ27-264 CFTR-mCherry (red, Δ27-264 CFTR) and F508-des CFTR-GFP (green, F508-del). Co-transfection of F508-DEL CFTR-GFP and Δ27-264 CFTR-mCherry occurred in 23.5% of the cells (35/150); of the cells stained for KDEL (purple), 100% (15/15) showed co-localization or close association between Δ27-264 CFTR and F508-del Representative extended-focus images are shown, and data were selected from one of four independent experiments.