Confocal microscopic analyses further showed that at one hour after incubation, the CpG-Stat3 siRNA colocalized with TLR9 within perinuclear endocytic vesicles (Fig. 2c , two top rows; and Supplementary Fig. 4 ). This colocalization diminished at 2 and 4 h after CpG-siRNA treatment (Fig. 2c , two top rows. Previous studies have demonstrated that binding of the Dicer nuclease to the siRNA oligonucleotide is required for further siRNA processing to shorter 21mer fragments that mediate RISC complex-dependent mRNA degradation 37 . We observed transient colocalization of the CpG-Stat3 siRNA with Dicer within 2 h after adding the oligonucleotide to cultured DCs (Fig. 2c , two bottom rows and Supplementary Fig. 4 ). The colocalization of CpG-Stat3-siRNA and Dicer became weaker by 4 h (Fig. 2c ) and undetectable after 24 h (data not shown).