POU5F1 and primitive neuroectodermal tumor: In the current study we sought to developmentally reprogram an established metastatic EWS cell line sourced from a patient-derived primitive neuroectodermal tumor (PNET), designated CHLA-10 (May et al., 2013), via nucleofection-mediated delivery of an EBNA1-based 4 factor (OCT3/4, NANOG, SOX2, and KLF4) episomal construct (Figure 1A).