Expression of different Ikaros isoforms. (A) Schematic diagram of the full-length Ikaros cDNA and the different isoforms produced in our samples by alternative splicing. (F) N-terminal zinc-fingers show DNA-binding activity, and C-terminal zinc fingers mediate dimerization of the protein. Ex indicates exon. (B) Bands generated by RT-PCR using primers derived from exons 2 and 8 and corresponding to the alternatively spliced products of the Ikaros pre-mRNA transcript. The left lane is the molecular size marker, marker VI Roche; lane 2, Ik6 expression; lane 3, coexpression of Ik1, Ik2, Ik4, and Ik6. (C) Sequence analysis of the Ik6 isoform in which exon 3 is juxtaposed with exon 8 and the novel Ik isoform (Ik6Δ) previously unreported, in which exon 3 is directly juxtaposed with exon 8 maintaining the frame (E). (D) Bands generated by RT-PCR; in lane 1 is the molecular size marker, marker VI Roche; in lane 2 is Ik6 (255 bp); in lane 3 is Ik6Δ (135 bp).