MDM2 and osteosarcoma: For instance, CircSAMD4A is highly expressed in osteosarcoma (OS) tissues and promotes cell proliferation and enhances cell stemness characteristics by sponging miR-1244 and regulating MDM2 expression in OS, which suggests that circSAMD4A/miR-1244/MDM2 axis may be a promising therapeutic target for OS therapy [99].