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Figure S2. GFPRab21 induces adhesion to collagen and does not influence transferrin traffic. (A) GFP-Rab21-transfected MDA-MB-231 cells were labeled with 10 µg/ml Alexa 555-conjugated transferrin (Invitrogen) on ice for 30 min. The cells were washed, and bound transferrin was chased at 37°C in the presence of 50 µg/ml unlabeled transferrin (Sigma-Aldrich) for the indicated times (10-60 min) before fixation and microscopy. (top) Fluorescence intensities on the red channel relative to the cell area (arbitrary units) in transfected and nontransfected cells in the same sample (mean ± SEM; n = 30-40). (bottom) GFPRab21 expression levels do not significantly correlate with internalized transferrin levels in transfected cells. (B) GFP- or GFP-Rab21-transfected MDA-MB-231 cells were allowed to adhere for 45 min to different matrixes as indicated. The number of adherent green cells was scored with Acumen cell scanner 488 nm (mean ± SD; n = 4).