Future work will focus on dissecting the contributions of specific HDACs, with an initial focus on the class 1 enzymes (HDAC1, HDAC2, HDAC3, and HDAC8) due to the sensitivity of Ewing sarcoma cell lines to the class 1 HDAC inhibitors romidepsin and entinostat, as well as a published CRISPR screen that identified the sensitivity of Ewing sarcoma cell lines to the loss of class 1 HDACs (59, 61). This evidence concerns the gene HDAC9 and Ewing sarcoma.