Flow-cytometric detection of transgene expression in red blood cells and platelets. Gating on red blood cells and platelets was based on scatter characteristics (left panel). Transgene-expressing red blood cells (upper panels) and platelets (lower panels) were detected in all 3 dogs. Because of the overlapping positive and negative populations due to low fluorescence intensity, especially in red blood cells, the percentages displayed most likely underestimate the actual percentage of GFP/YFP-expressing cells.