Thus, given the high mortality rate and the possible cancer stem cell involvement in metastasis and tumor recurrence (Awad et al., 2010), undifferentiated EWS-iPS cells themselves may also provide a valuable tool to investigate EWS tumor development and modes of drug resistance via identifying the epigenetic modifications and molecular pathway alterations contributing to their drug resistance—current avenues of research that we are pursuing. Here, EWSR1 is linked to neoplasm.