RBL-2H3 mast cells were imaged during antigen stimulation. Each video represent either control cells (vector shRNA) or GEF-H1 knockdown cells (GEF-H1 shRNA). Cells were labelled with Lysotracker Red and Life-act Ruby to track granule dynamics and F-actin dynamics, respectively. Cells were also imaged in DIC bright-field mode to show membrane changes.