EWSR1 and Ewing sarcoma: In 2021, Tanaka and Nakamura successfully described the EWSR1-FLI1-expressing mouse model of Ewing sarcoma by selecting chondrogenic progenitor cells, mouse embryonic superficial zone (eSZ) cells purified from embryos, transfecting with EWSR1–FLI1 plasmid, and transplanting them into Balb/c mice [93].