Cis-Golgi remains partially resistant to BFA in Surf4/ERGIC-53– and p25-depleted cells. HeLa cells transfected with Surf4/ERGIC-53, p25 siRNA, or control siRNA were treated with 10 μg/ml BFA for 30 min. Cells were processed for immunofluorescence microscopy by using anti-GM130 and anti-KDEL-receptor (A), anti-GM130 and anti-p115 (C), or anti-giantin and anti-GPP130 (D) antibodies. (B) Quantification of cells showing BFA resistant cis-Golgi according to GM130 staining. Results are means ± SD (n = 3). Bars, 10 μm.