Only the junctions exon 4 and exon 5 are shown because the other exon-exon junctions were normal. Nucleotides in exons are in uppercase, those in introns in lowercase. For each spliced product, the utilized donor and acceptor sites are in bold. For the wild-type construct, 100% of mRNAs were normally spliced between exons 4 and 5. For cells transfected with the IVS4 + 1 G → T mutant, various abnormal mRNAs were found with different frequencies in a total of 143 clones out of 145. In 2 clones, the mRNA was normally spliced between exons 4 and 5.

mRNA: messenger RNA.