Effect of PNAs on the splicing of intron2. Comparison of PNAs 2549, 2406, 2551 and 2553 in terms of splicing inhibition of intron2 in mdm2 pre-mRNA. JAR cells were transfected with PNAs (2 μM) for 24 h and subjected to RT-PCR analysis using extracted total RNA. RT-PCR was performed with primer sets B and H (see Table 2), for intron2 in mdm2 pre-mRNA (90 bp) and β-actin (223 bp) (as internal control), respectively. RT-PCR results with 27 PCR cycles are shown. The numbers under the figure indicate the relative amount (normalized to β-actin) of the target mdm2 splicing variant.