Fig. 4. Expression of a VWF-EGFP fusion protein in HUVECs reveals that newly formed WPBs are Rab27-negative. HUVECs were nucleofected with pre-pro-VWF-EGFP, replated onto gelatine-coated glass coverslips and allowed to recover for either 5 hours (A-C) or 24 hours (D-F), after which they were fixed and processed for immunocytochemistry as described in Materials and Methods. The images shown are single confocal sections of endogenous Rab27 immunoreactivity (A,D and red in C,F) and EGFP fluorescence/immunoreactivity (B,E and green in C,F). Arrowheads indicate examples of green-fluorescent WPBs that are not immunoreactive for Rab27, asterisks indicate examples of Rab27-immunoreactive WPBs that do not contain EGFP and arrows indicate examples of WPBs that are positive for both EGFP and Rab27 immunoreactivity. Scale bars, 10 µm.