MAPK1 and neoplasm: Strand-specific RT-PCR assays using RNA aliquots from tumor tissue samples showed that 4 intronic transcripts have antisense orientation relative to the protein-coding mRNA: PPP3CB, ATF2, TGFBR2 and MAPK1. Antisense transcripts originated in PPP3CB intronic regions were also detected in MIA PaCa-2 cells.