(d-f) MDA-MB-231 cells expressing MT1-MMP-pHluorin transfected with scrambled siRNA (siNC) or siRNA against RAB2A were seeded on type I collagen, and images were acquired for 20 min period by TIRF microscopy. Frequency of MT1-MMP-pHluorin exocytic events was quantified (e). The corresponding time-lapse series are shown in Movie 1, while an entire cell shown in Movie 2. Efficacy of RAB2A gene silencing was verified by qPCR (f). Bars, 2 μm. **, P < 0.01. 