EWSR1 and mesenchymal cell neoplasm: It has been previously reported that mesenchymal stem cells (MSCs) exhibit a high potential for transformation into mesenchymal tumors (Vishnubalaji et al, 2019) and could be a possible source of trans-reprogramming of RMS into Ewing sarcoma by introducing the EWS-FLI1 gene (Hu-Lieskovan et al, 2005).