Fig. 6. Δ264 and Δ27-264 CFTR interact with F508-del. CFBE41o^- cells were plated on coverslips and transfected with Δ264 (A) or Δ27-264 CFTR-mCherry (B) and ΔF508 CFTR-GFP. At 48 h post-transfection, the cells were fixed, and slides were mounted using mounting medium without anti-fade. Acceptor photobleaching was performed. Samples were bleached using the 561nm laser line of a Zeiss LSM 510 confocal microscope. Samples were then excited using the 488-nm laser line, and changes in green fluorescence were measured. (A) The left column is the image before photobleaching with a 561-nm laser, and the right column is the image after photobleaching. FRET efficiency was calculated by measuring the changes in the 488-nm signal before and after photobleaching. The statistical analysis of the FRET efficiency was obtained from the images. Results are means ±SE (n = 4). The FRET efficiency for the control sample is 0, since there was no green signal present to measure because of the single transfection.