ATR and B-cell chronic lymphocytic leukemia: The expression of the regular and alternative BRD9 splice variants was also analyzed in 3 SF3B1WT cell lines, MEC1, PGA1, and HG3 (all CLL), and 3 SF3B1MUT cell lines, CII (CLL), HNT34 (AML), and MEL202 (UVM).