Although the development of specific LSD1 inhibitors is still in its infancy, treatment of Ewing sarcoma cell lines with the specific and non-competitive reversible LSD1 inhibitor HCI-2509 (Figure 1) comprehensively reversed the transcriptional signature driven by both EWS/FLI and EWS/ERG27,48. The gene discussed is FLII; the disease is Ewing sarcoma.