We further tested EZH2 inhibition in primary leukemia cells isolated from patients across various AML genotypes (n = 15; Fig. 2, g and h; and Fig. S3 c), where significant reduction of colony formation was seen, in contrast to the minimal effects of GSK343 on the clonogenic function of normal primary CD34+ hematopoietic stem cells (HSCs; n = 3; Fig. S3 d). Here, CD34 is linked to leukemia.