Figure 3. Effect of over-expression of microRNAs on Bcl-2 expression in HEK-293 and NIH/3T3 cells. Immunocytochemistry analysis of miRNA (mmu-miR-34a, mmu-miR-30e and mmu-miR-181a-1*) suppression of endogenous Bcl-2 in both 293 (A) and NIH-3T3 (B) cell strains. The cells transfected with plasmid showing fluorescence and Bcl-2 immunostaining are from the respective identical fields. In each set (HEK-293 and NIH-3T3 cells), miRNA-transfected cells have significant Bcl-2 staining reduction, compared to Bcl-2 signal in neighboring cells lacking miRNA transfection. This pattern does not pertain in scrambled plasmid-transfected 293 or NIH-3T3 cells; scrambled plasmid-transfected cells show Bcl-2 staining intensity identical to un-transfected cells. The histograms show the quantification of fluorescence for plasmid transfection and the corresponding Bcl-2 expression in the cells. (**p<0.01, **p<0.0001; all histograms represent average ± std.dev.)