CHD4 depletion dramatically decreases the tumor-forming behavior of AML cells and modulates expression of genes associated with tumor colony formation. CHD4-depleted cells were inhibited in their ability to engraft into the NSG mice. CHD4 depletion severely reduced the ability of U937 and MV4-11 cell lines to form colonies in soft agar. (A) Representative images (20×) of colonies. (B) Quantitation of AML colonies (*P < .05, n = 3). (C) Microarray arrays were performed to determine the gene expression alterations associated with CHD4 depletion. Ingenuity Pathway Analysis software was used to interpret the data and predicted a significant decrease in the colony-forming potential in both U937 and MV4-11 (activation Z score of −2.044 and −2.002, respectively). (D) Depletion of CHD4 in CD34⁺ hematopoietic progenitors isolated from 3 normal donors did not result in a significant decrease in colony formation.