Cells as in (A) were fed at 1 bead per cell with pHrodo conjugated beads that increase fluorescence at low pH. After 4 hours of incubation, whole cells were harvested and run through flow cytometry to measure fluorescence of eaten beads. For analysis, the background fluorescence of uneaten beads was subtracted from the resulting gMFI and the fold change of 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. Also shown are histograms of whole cells compared to background fluorescence of pH beads. 