SETD2 loss leads to resistance to DNA-damaging chemotherapy agents. (A) Diagram of SETD2 nonsense, frameshift, or missense mutations reported in pediatric ALL (Dana-Farber Cancer Institute⁶  and St. Jude Children's Research Hospital⁴⁶  cohorts, top) or in cancers of hematological or lymphoid tissue origin (Catalogue of Somatic Mutations in Cancer [COSMIC],⁴⁷  bottom). (B) Western blot for H3K36me3 of MOLM-13 subclones with SETD2 deletions and isogenic control. The H3K36me3 level normalized to actin is shown. Full western blot with additional subclones are shown in supplemental Figure 1C. (C) H3K36me3 levels for highly expressed and nonexpressed genes in MOLM-13 isogenic clones, normalized over gene body length between the vertical lines. (D) CellTiter-Glo was used to determine the percentage of cell viability after 72 hours of cytarabine, (E) 6-TG, (F) doxorubicin, (G) etoposide, and (H)l-asparaginase. (I) MOLM-13 SETD2 clone 1 was transduced with an RFP⁺ lentivirus, competed with isogenic control 3 in a 1:20 ratio, and treated with cytarabine, 6-TG, or vehicle for 18 days and assessed by flow cytometry every 3 days, where RFP was used as a read-out for the percentage of SETD2-mutant cells. (J) A similar competition experiment was performed as described in panel I with cells treated with l-asparaginase or vehicle for 18 days and followed by flow cytometry. TES, transcriptional end site; TSS, transcriptional start site.