Fig 1: SF3B1 activity is critical for CHEK2 levels and DNA damage response.(A) γH2AX level in CUTLL1 and JURKAT cells treated with 3 nM E7107 for 24 hours. (B and C) Representative comet assay photos from CUTLL1 cells treated with 3 nM E7107 for 24 or 48 hours [quantification of (C) in the right panel, n = 45]. **P ≤ 0.01. (D) Metagene analysis of MapR signal around the transcriptional start site in 3 nM E7107 treatment for 24 hours in CUTLL1. DMSO, dimethyl sulfoxide. (E) Metagene analysis of normalized transient transcriptome sequencing (TT-seq) reads for protein-coding transcripts (±3-kb area, 3 nM E7107, 15 min). (F) Scatterplot of splicing changes in E7107 versus vehicle (FDR < 0.05 and PSI > 0.1). (G) Sashimi plots representing exon-exon junctions for CHEK2 upon treatment of CUTLL1 cells with E7107 (3 nM, 24 hours). (H and I) PCR for the detection of CHEK2 exon 7/9 skipping in shSF3B1 CUTLL1 cells (H) or upon treatment with 3 nM E7107 [24 hours, (I)]. (J) CHEK2 protein levels in shSF3B1 CUTLL1 cells or upon treatment with E7107 (1.5 and 3 nM) for 24 hours. (K) PCR for the detection of CHEK2 exon 7/9 skipping in shUPF1 CUTLL1 cells treated with E7107 (3 nM, 24 hours) and CUTLL1 cells treated with 3 nM E7107 or 3 nM E7107 + CHX (50 μg/ml) for 8 hours (w e, with exon). (L) Growth of shCHEK2.1- and shCHEK2.2-expressing CUTLL1 cells (n = 3). (M) CHEK2 protein levels in shSF3B1 CUTLL1 cells treated with doxycycline (Dox; 1.5 μg/ml, 48 hours) to induce ectopic expression of CHEK2.