Human fibroblasts in addition to other types of sarcoma cell lines, such as rhabdomyosarcoma (RD), osteosarcoma (HS‐Os‐1), and clear cell sarcoma (SU‐CCS‐1), were also treated with TAE226, and they definitely proved to be more resistant than EWS cells. This evidence concerns the gene EWSR1 and rhabdomyosarcoma.