MTUS1 and breast cancer: Significant correlation was observed between Affymetrix probeset intensities and expression levels of ATIP3 (r2 = 0.83) (Fig. 1F), but not ATIP1 transcripts (r2 = 0.01) (Fig. 1G), indicating that ATIP3 is the major MTUS1 splice variant whose expression is regulated in breast cancer.