SNPH is required for activity-dependent immobilization of axonal mitochondria. (A–D) Kymographs (A and B) and quantitative analysis (C and D) showing the motility of axonal mitochondria and late endosomes along the same axons of snph^+/+ and snph^−/− neurons before and after treatment (2 min) with 50 mM KCl and 10 µM FPL 64176. Hippocampal neurons were cotransfected with DsRed-Mito and YFP-Rab7 at DIV9 followed by imaging at DIV12. Vertical lines in kymographs represent stationary mitochondria; slanted lines or curves to the right (negative slope) represent retrograde movement; curves to the left (positive slope) indicate anterograde movement (also see Fig. S1 and Videos 1, 2, and 3). (E) The relative motility of dendritic mitochondria in snph^+/+ and snph^−/− hippocampal neurons before and after treatment (2 min) with 50 mM KCl and 10 µM FPL 64176. Data were quantified from numbers of neurons indicated in parentheses (C and D) or within bars (E) in three independent experiments. Bars, 10 µm. Error bars show SEM. Student’s t test.