RT-PCR analysis reveals exon skipping and intron inclusion in the FPGS cDNA. PCR was performed on the FPGS gene using 3 sets of forward primers with EX13-dw. (A) Primer ex9-10 residing in the junction between exons 9 and 10 (lanes 1, 3, 5, 7), primer ex9-11 residing in the 3′-end of exon 9 and 5′-end of exon 11 and thus being diagnostic of exon 10 skipping (lanes 2, 4, 6, 8). (B) PCR was performed to corroborate the presence of intron 10 in CEM-7OH MTX and Molt-4-7OH MTX cDNA using a forward primer (ex10int10) on the junction between exon 10 and intron 10. (C) TNFα as a control gene for normal splicing.