2.1. Cell Lines and Reagents

The embryonal RMS cell line RD (ATCC, Manassas, VA, USA) and the alveolar RMS cell line RH30 (DSMZ, Braunschweig, Germany) as well as the primary human skeletal muscle cells (SkMC) (PromoCell, Heidelberg, Germany) were cultured in DMEM high glucose 4.5 g/L medium (Sigma Aldrich Chemie GmbH, Taufkirchen, Germany) supplemented with 1% L-glutamine (Biochrom, Berlin, Germany), 10% heat-inactivated fetal bovine serum (Biochrom, Berlin, Germany), and 1% penicillin/streptomycin (Biochrom, Berlin, Germany) in a humidified atmosphere containing 5% CO₂ at 37 °C. Only early passages (after purchase or authentication) which were tested to be negative for mycoplasma contamination (MycoAlert; Lonza, Cologne, Germany) were used for the current study. EZH2 inhibitors EPZ005687 (Cayman Chemical Company, Ann Arbor, MI, USA), DZNep (Cayman Chemical Company, MI, USA), and AdOx (Sigma Aldrich Chemie GmbH, Taufkirchen, Germany) were used as indicated.