POU5F1 and osteosarcoma: Stemness-related genes Nanog and Oct4 were highly expressed in human osteosarcoma CD133+ cell subsets with lower expression of TREX1; the biological characteristics identification experiment showed that human CD133+ cell subsets with low TREX1 expression could form tumorspheres, the number of colony forming was more, the cell proliferation ability was strong, the osteogenic and adipogenic differentiation potential was big, the tumor-forming ability in nude mice was strong, and the sensibility of chemotherapeutics drugs on cisplatin was low.