MEF2D knockout promotes myeloid differentiation and delays in vivo leukemogenesis of MLL-r AML. (A) Analysis of apoptotic cells in MOLM-13 cells 6 days after sgRNA-mediated knockout of MEF2D, relative to transduction of the sgLuc control sgRNA. (B) Wright-Giemsa of MOLM-13 cells 6 days after sgRNA-mediated knockout of MEF2D, relative to transduction of the sgLuc control sgRNA. (C) Representative flow cytometry analysis of differentiation markers CD14 (left) and CD33 (right) in MOLM-13 cells 6 days after sgRNA-mediated knockout of MEF2D, relative to transduction of the sgLuc control sgRNA. (D) Frequency of population with high myeloid differentiation markers CD14 (left) and CD33 (right) was measured by flow cytometry. (E) Luminescence of MOLM-13 (Cas9+, luciferase+) cells in the recipient mice at day 15 after xenotransplantation. (F) Percentage of human CD45+ cells in the peripheral blood of mice receiving MOLM-13 cells transduced with indicated sgRNAs at 10,15, 26-, and 32-day post injection. *All mice receiving MOLM-13 cells transduced with control guide RNA (sgROSA26) were dead before the day 26 measurement. (G) Kaplan–Meier survival curves of recipient mice transplanted with MOLM-13 cells expressing indicated sgRNAs.***P < .001; na, not analyzed.