Fox-1 and Fox-3, but not their ΔRRM isoforms inhibit the inclusion of Fox-2 exon 6. (A) RT-PCR analysis of the endogenous Fox-2 exon 6 splicing. Human HEK293 and mouse neuroblastoma N2A cells were transiently transfected with FLAG-tagged Fox-1, Fox-1ΔE11, Fox-3, and Fox-3ΔE8 as indicated. (Lanes −) A control transfection with vector not bearing a protein reading frame was carried out in parallel. (Lanes −/−) Samples prepared similarly to the adjacent lanes −, except that reverse transcriptase was omitted. The fraction of Fox-2 mRNA excluding exon 6 is shown below each lane as a percent of the total. (B) The recombinant proteins were detected by Western blotting using anti-FLAG and anti-FoxRRM antibodies. Anti-U1 70K Western is carried out in parallel as a loading control.
