Semiquantitative RT-PCR on cDNA from transfected HeLa cells with plasmids BX, BX3 and BX4. (a) Semiquantitative RT-PCR using T7/EBPR primers (left) and scheme of the transcript corresponding to each band is shown (right). (b) Percentage of transcripts including exon 3 versus transcripts lacking it, i.e. (1+2)/(3+4). (c) Percentage of transcripts including exon 4 versus transcripts lacking it, i.e. (1+3)/(2+4). Each value is the mean ± S.E. of two independent experiments, each of which was replicated three times. * when p < 0.05.