Pharmacologic inhibition of PRMT1 blocks MLL-r ALL cell survival and growth. (A) Western blot for FLT3 and R972/973me2a in MLL-r ALL samples (n = 7) treated with vehicle or MS023 (5 μM). (B-C) Western blot of endogenous R972/3me2a expression in MLL-r ALL cell lines (n = 4) (B, upper panel) and MLL-r ALL samples (n = 7) (C, upper panel). Bottom panels show corresponding correlation analysis of R972/973me2a expression and MS023 IC50 (the half maximal inhibitory concentration). (D) Apoptosis of shCtrl- or shPRMT1-transduced primary MLL-r ALL cells treated with vehicle or MS023. (E) PRMT6 gene expression was analyzed between non–MLL-r and MLL-r ALL specimens in indicated microarray data sets (GSE13204 and GSE34861). (F) Apoptosis of indicated subsets of normal PBSCs (n = 3) in MLL-r ALL samples (n = 7) treated with vehicle or MS023. Error bars represent standard error of the mean. *P < .05; **P < .01; ***P < .001.