Moreover, given that SPOP depletion did not affect EWS–FLI1 mRNA abundance (Figure S1L, Supporting Information), and treatment of MHH‐ES‐1 (Figure S3C, Supporting Information) or A673 (Figure S3D, Supporting Information) cells by a BRD4 inhibitor JQ1 did not affect EWS–FLI1 protein levels, it seems that the SPOP/BRD4 signaling axis identified in prostate cancer may not regulate EWS–FLI1 protein stability in Ewing sarcoma. Here, FLI1 is linked to Familial prostate cancer.