The tPA-EGFP-containing organelle does not recruit endogenous or expressed Rab27a. (A) An individual HUVEC triple labeled with specific antibodies to tPA (green), Rab27a (red), and VWF (blue). Grayscale images of the regions i and ii are shown on the right. (B) Twenty-four hours after Nucleofection with tPA-EGFP (green; EGFP fluorescence) and myc-Rab27a (red). tPA-EGFP is seen in Rab27a-negative puncta and also occasionally in some WPBs, identified by their distinctive rod-shape (large arrowheads). (A-B) Grayscale inserts: regions indicated by white boxes on the color images.