SF3B1 and hematologic disorder: Based on the COSMIC v97 database, SF3B1 is recurrently mutated in many different types of cancers with a particularly high frequency in hematological malignancies at the K700E position on exon 15 (Fig. 1A–C); refs. 10, 11) While several isogenic SF3B1 mutant cell lines have been generated (Supplementary Table S1; refs. 12–15), the majority of these do not model the SF3B1 mutation in the proper cancer contexts.