Inhibition of G9a methyltransferase activity by UNC0638 in adult human erythrocytes stimulates fetal hemoglobin production. (A) The percentage of HbF, relative to total hemoglobin (HbF + HbA), measured in culture day 21 control, phase 1, phase 2, phase 3, and phase 1-3 cells treated with 1.0 µM UNC0638. (B) The percentage of HbF, relative to total hemoglobin (HbF + HbA), in culture day 21 control and phase 2 cells treated with depicted concentrations of UNC0638. (C) Quantitative analysis of the percentage of GPA⁺ cells measured by fluorescence-activated cell sorter analysis of control and phase 2 cells treated with depicted concentrations of UNC0638 at culture day 14. Representative flow cytometric dot plots of (D) control cells and (E) 1.0 µM UNC0638 phase 2 treated cells at culture day 21 stained for fetal hemoglobin. In panels A-C, error bars indicate standard error of the mean (SEM); n = 3 independent donors for each condition. *Student t test values of P < .05 compared with control. Ave, average.