Cells as in (A) were incubated with or without 1 µg/ml dox overnight to induce Rab39a expression. 1x106 cells were incubated on ice with 4 beads/cell of biotinylated-Ova-beads for bead attachment. Cells were then transferred into 37oC media containing 5 µM CellROX Deep Red. After 4 hours of incubation, unfixed phagosomes were extracted and analyzed via flow cytometry for CellROX fluorescence. For analysis, the background fluorescence of unstained beads was subtracted from the resulting phagosome gMFI and the fold change (dox/no dox) was calculated. Three independent experiments were combined. P<0.05 using two-tailed ratio-paired Student's t-test. Error bars show SD between experiments. 