PTBP1 and osteosarcoma: Following detection of PTBP1 expression in DXR-resistant osteosarcoma tissues and cells, we constructed DXR-resistant osteosarcoma cell lines (U2OS/DXR, MG63/DXR, HOS/DXR) with siRNA targeting PTBP1 and their parental cells (U2OS, MG63, HOS) with expression vectors containing PTBP1 to further explore the effect of PTBP1 on chemoresistance of osteosarcoma cells.