Rescue of Meis1 gene expression abrogates sensitivity to menin-MLL1 inhibition in NUP98-fusion leukemia. (A) Quantitative PCR for Meis1 mRNA in NUP98-HOXA9 mouse leukemia cells engineered to overexpress Meis1 and treated with DMSO or 2 μM VTP50469. Data are representative of 3 independent experiments. Two-way ANOVA with Dunnett’s multiple comparisons test was performed, ****P < .0001. (B) Immunoblot for Meis1 protein in NUP98-HOXA9 mouse leukemia cells engineered and treated as in (A). (C) NUP98-HOXA9 mouse leukemia cells engineered as in (A) and treated with an escalating dose curve of VTP50469. Data are representative of 3 independent experiments. (D) Expression of CD11b on NUP98-HOXA9 mouse leukemia cells overexpressing Meis1 and treated with an escalating dose curve of VTP50469. Data are representative of 3 independent experiments. Two-way ANOVA with Dunnett’s multiple comparisons test was performed, ****P < .0001. (E) Quantitative PCR for Meis1 mRNA in NUP98-HOXA9 mouse leukemia cells engineered to constitutively express dead Cas9 (dCas9) and transcriptional activators MS2, p65, and HSF1 with small guide RNAs targeting Meis1 or luciferase and treated with 2 μM VTP50469. Data are representative of 3 independent experiments. Two-way ANOVA with Dunnett’s multiple comparisons test was performed, ****P < .0001. (F) Immunoblot for Meis1 protein levels in cells engineered and treated as in (E). (G) NUP98-HOXA9 mouse leukemia cells engineered as in (E) and treated with an escalating dose curve of VTP50469. Data are representative of 3 independent experiments.