Spastin and IST1 regulate endosome-to-Golgi traffic. (A) Anti-CD8 antibody uptake experiments in HeLa cells stably expressing CD8-ciM6PR and GFP-GOLPH3 (a Golgi marker), and subjected to IST1 or spastin KD. Cells were fixed at the times indicated, and CD8 and GFP signal were visualized by confocal immunofluorescence microscopy. Mean ± SEM colocalization between the markers (Pearson’s correlation) at 30 min is shown in the histogram (n = 6). Bars, 10 µm. (B and C) Wild-type HeLa cells or HeLa cells stably expressing the siRNA-resistant spastin proteins indicated were subjected to endogenous spastin KD, fixed, and visualized for M6PR and LAMP1. Mean ± SEM colocalization was plotted. n = 4 (B) or 5 (C). In B and C, p-values between the HeLa mock and all other mock conditions were not significant. P-values generated by two-tailed Student’s t test.