In vitro, miR-503 was also lower in osteosarcoma cells than that in normal osteoblasts cells, and overexpression of miR-503 suppressed the proliferation and invasion of osteosarcoma U2OS cells, thus, it acted as a tumor suppressor in osteosarcoma via inhibiting its target, IGF-1R. Here, IGF1R is linked to osteosarcoma.