EWSR1 and Ewing sarcoma: Our findings in “bulk” Ewing sarcoma cell populations, known to be composed predominantly of cells with high EWS/Fli1 expression [11], suggest that KDM5A and PHF2 may play an important role in helping restrain the metastasis-repressive effects of EWS/Fli1, and as such to help maintain metastatic competency in Ewing sarcoma.