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. Author manuscript; available in PMC: 2015 Apr 26.
Published in final edited form as: Cell Tissue Res. 2014 Jan 7;356(1):147–157. doi: 10.1007/s00441-013-1767-7

Fig. 1.

Fig. 1

Caveolae-mediated uptake of albumin. a Western blot analysis of siRNA-treated HUVEC was performed to quantify caveolin-1 protein levels. Caveolin-1 siRNA-treated HUVEC displayed significantly decreased caveolin-1 protein levels when compared to CTL siRNA-treated cells. b Expression of caveolin-1 in HUVECs was also examined via immunofluorescence staining using an antibody specific to caveolin-1. c HUVECs were treated with control and caveolin-1 siRNA and then incubated with fluorescently labeled albumin (rhodamine-labeled, red) alone for 0, 15, 30 and 60 min or in the presence of unlabeled albumin (competition for 60 min). Colocalization (yellow) of albumin and caveolin-1 (FITC-labeled, green) was evident (white arrows) in cells treated with control siRNA. The uptake of albumin (red) by HUVEC was exclusively mediated by the caveolae pathway. Unlabeled albumin competed with labeled albumin internalization in the control siRNA treated cells (competition for 60 min). d siRNA-treated HUVEC were incubated with fluorescently labeled albumin (rhodamine, red) and fluorescently-labeled transferrin (FITC, green) for 0, 15, 30 and 60 min. Albumin was taken up only via caveolae. In the control siRNA-treated cells, transferrin and albumin did not colocalize, confirming the independent internalization of albumin (caveolae) and transferrin (clathrin-coated pits)