Pu.1 or Runx1 genetic loss rescues erythroid differentiation inhibition induced by blocking LSD1 activity. (A) CD71 and CD235a flow cytometric analysis of 3 independent nontargeting sgRNA-infected cells (wild-type [WT]), 4 independent PU.1^−/− HUDEP2 clones, or 4 HUDEP2 Runx1^−/− clones treated with DMSO (control) or 300 nM CCG50. Data are the average percentage of CD71⁺CD235a⁺ cells from multiple clones in supplemental Figure 15. Impaired erythroid differentiation (as reflected by the reduced percentage of CD71⁺CD235a⁺ cells) in the WT group after CCG50 treatment was rescued by PU.1 or RUNX1 knockout. (B) mRNA levels of γ-globin, β-globin, GATA1, and PU.1 in random sgRNA control cells and P3-18 (PU.1^−/−) or R2-47 (RUNX1^−/−) LOF clones after treatment with DMSO or 300 nM CCG50. Data are mean ± standard deviation. *P < .05, **P < .01, ***P < .001, unpaired Student t test.