Figure 1. Prediction and verification of the IRA1/RGS17 fusion resulting from a chromosome translocation. A) Schematic representation of the IRA1/RGS17 fusion. Boxes represent the exons, and broken lines the introns. The fusion event is indicated by an arc. Arrows indicate the transcription start sites. Exons are numbered as they occur in the original genes. Primers for the reverse transcriptase (RT)–PCR reaction are indicated (T530 and T531). ORFs (open reading frames) are marked with grey boxes. B) RT-PCR detection of the fusion transcripts in MCF7 cells. The fusion gene transcripts for the previously known BCAS4/BCAS3 and the predicted IRA1/RGS17 fusions were detected in the cells. The β actin (ACTB) was used as the positive control. The product sizes of ACTB, BCAS4/BCAS3, and IRA1/RGS17 are 600, 328, and 367 bp, respectively. C) Detection of the 3;6 translocation in MCF7 cells by a fluorescence in situ hybridization (FISH) experiment. A representative result is presented. The IRA1 gene (red) and the RGS17 gene (green) are on the chromosomes 3 and 6, respectively. Besides two copies each of chromosomes 3 and 6, a 3;6 translocation was detected (white arrow).