Fig. 4.

The EMCV IRES element impairs miRNA repression. HeLa cells were cotransfected with mRNA and miRNAs as in Figs. 1 and 2. (A) Schematic of the R-luc-4 sites mRNAs used in this experiment: They carry either the standard 5′ UTR or the EMCV IRES, either with or without a poly(A) tail; all are A-capped. (B) Normalized R-luc activity from the four versions of R-luc-4 sites mRNA (no miRNA added; expression from the EMCV&tail mRNA is set to 1.0). Averaged results from two (A-cap) to four experiments are shown with standard deviation where appropriate. (C) Repression by a miRNA (calculated as in Figs. 1B and 2C). Averaged results from three to five experiments are shown with standard deviation (filled bars, CXCR4; open bars, let-7).