Granule tracks were analyzed using Volocity software as described in Materials and Methods. Granule track length (A), track velocity (B), displacement (C), and displacement rate (D) from 14 events pre- (LysoTracker Red, left) and post-degranulation (pHlourin-LAMP1, right) are shown. Representative NK92 lytic granules from Figure 3A are indicated by open diamonds. Mean ± SD are shown. Differences between Lysotracker Red and pHlourin-LAMP1 granule tracks were significant (p <0.0001, two-tailed t test). Results are from 4 independent experiments.