We further evaluated CpG-Stat3 siRNA-FITC uptake by DC 2.4 mouse DCs. Flow cytometry and fluorescent microscopy indicated that without transfection reagents, the CpG-Stat3 siRNA-FITC was internalized by DC 2.4 cells, with kinetics similar to that CpG-ODN alone ( Fig. 2b -two top rows and Supplementary Fig. 3 ) and reported previously 36 . By 60 min, greater than 80% DC 2.4 cells were positive for uptake of the conjugate, which was confirmed by confocal microscopic analysis. The uptake of the CpG-Stat3 siRNA-FITC was dose dependent (Fig. 2b, bottom row) .