(a) Doxycycline-inducible RAB2A-shRNA MCF10.DCIS.com cells were incubated on a thick layer of Matrigel for 4 days to allow spheroid formation in the absence (CTR) or presence (shRAB2A) of doxycycline. Cells were stimulated with 5 ng/ml EGF and 20 ng/ml HGF (EGF+HGF) or left starved (STV) for 9 days. Representative phase contrast light microscopy images are shown. Invasive activity of the cells was expressed by circularity (with a value of 1 representing perfect circularity = no invasion) of each acini. Bar, 100 µm. 