PARP1 and Ewing sarcoma: In a previous paper, Brenner and colleagues reported that in prostate cancer PARP was a cofactor for wild-type ETS transcription factors, which makes up one half of the defining translocation-based fusion transcription factor of Ewing’s sarcoma, and that PARPi treatment of ETS positive prostate cancers disrupted their growth (Brenner et al., 2011; Legrand et al., 2013).