Total cell lysates from human RMS cells and xenografts were obtained following lysis in SDS lysis buffer. Western blot analysis was performed similar to Ignatius et. al., 2017 (21 (link)). Membranes were developed using an ECL reagent (Western Lightning Plus ECL, PerkinElmer; or sensitive SuperSignal West Femto Maximum Sensitivity Substrate, Thermo Scientific). Membranes were stripped, rinsed, and re-probed with the respective internal control antibodies. List of primary and secondary antibodies is included in supplementary data (Supplemental Table 2).