POU5F1 and neoplasm: To further and significantly extend these data, herein we introduced a reporter system to monitor the transcriptional activity due to SOX2 and/or OCT4 (SORE6) [29] in a model of undifferentiated pleomorphic sarcoma (UPS) and chondrosarcoma patient-derived cell lines thus analyzing for the first time the ability of isolated SOX2/OCT4-positive cells as tumor-promoting CSCs in sarcoma.