Mouse Fox-1 induces exon 9 skipping of hF1γ pre-mRNA via binding to GCAUG element. (A) The schematic representation of various hF1γ mini-genes. The Fox-1-binding sequence GCAUG and its mutated sequence CGAUG are shown as open and closed circles, respectively. (B) Transfection assays of various hF1γ mini-genes into CV-1 cells. The hF1γL (lanes 1–3), hF1γS (lanes 4–6), hF1γSmt (lanes 7–9) and hF1γSmt+3GCAUG mini-genes (lanes 10–12) were co-expressed with pCS2+MT vector (lanes 1, 4, 7, 10), Fox-1 (lanes 2, 5, 8, 11) and F-A mutant (lanes 3, 6, 9, 12). Splicing products were analyzed by RT-PCR. Splicing products are schematically shown on the right. All experiments were performed more than three times. Average percentage and SD of exon 9 exclusion are shown at the bottom of each lane. (C) Upper panel shows western blotting of cell extracts to detect Fox-1 proteins: Mock, Fox-1 and Fox-1 F-A, expressed from the pCS2+MT vector using the anti-Myc antibody. The positions of molecular size markers are shown on the right. Lower panel shows western blotting of the same cell extracts with anti-U2AF antibody as a loading control.