Effect of PNAs on the splicing of intron2 in mdm2 pre-mRNA. Splicing inhibition of three PNAs (PNA2545, 2547 and 2549) targeted to the 5'-splice site of intron2 in mdm2 pre-mRNA. JAR cells were transfected with PNA (2 μM) for 24 h and subjected to RT-PCR analysis by using extracted total RNA. RT-PCR was performed with primer sets C and H (see Table 2), for 3'-splice site of the intron2 (120 bp) and β-actin (223 bp) (as internal control), respectively. Results of RT-PCR with 27 cycles are shown. The numbers under the figure indicate the relative amount (normalized to β-actin) of the target mdm2 splicing variant.