BFA blocks sorting of SMS1 and 2. HeLa cells expressing GFP-SMS1 (A and D), GFP-SMS2 (B and E), CD4-GFP (C and F) were treated with BFA (5 μg/ml) for 8 hours (A-C). The cells were washed 6 times with growth media to remove BFA and allowed to recover for 3 h (D-F). Images were obtained using confocal microscopy. Calnexin is an ER marker, TGN46 is a Golgi marker, and Wheat Germ Agglutinin (WGA) is a plasma membrane marker.