Fig. 4. Expression of GFP-Rab21 wt causes enlargement of EEA1-positive endosomes. HeLa cells transfected with GFP-Rab21 wt (A-C), GFP-Rab21 Q78L (D-F) or GFP-Rab21 T33N (G-I) plasmids using calcium phosphate were fixed and labelled with anti-EEA1 antibodies and Texas Red-conjugated secondary antibodies (red in merge) before analysis by confocal fluorescence microscopy. GFP-Rab21 wt expression results in the formation of swollen endosomes that label intensely with anti-EEA1 antibodies (A-C). GFP-Rab21 Q78L expression also causes increased prominence of EEA1-positive endosomes (D-F) but these are not as distinct as those in cells expressing GFP-Rab21 wt. EEA1 labels smaller vesicles in nontransfected cells and those expressing Rab21 T33N (G-I). Arrows indicate colocalisation of GFP-Rab21 and EEA1, and asterisks represent transfected cells. Bars, 10 µm.