The MDM2 gene and PNA target positions. (A) The regions of mdm2 pre-mRNA used as targets for PNAs are indicated with thick bars under the exons ((a), (b) and (c)). Numbered boxes: exons; lines: introns. (B) The exact sequence position of PNAs targeted to the 5'-splice site of intron2 (a), 3'-splice site of intron2 (b) and 3'-splice site of intron3 (c) are shown. Intron sequences are in lower case.