ROR1-AS1 functioned as one sponge for miR-504. (A) The miR-504 expression in osteosarcoma cells (MG-63, U2OS and SAOS-2) and hFOB1.19 was detected by RT-qPCR. (B) ROR1-AS1 has potential binding sites of miR-504 by searching Starbase. (C) The miR-504 expression was detected in MG-63 cell after transfection with miR-504 mimic. (D) Ectopic expression of ROR1-AS1 suppressed miR-504 expression in MG-63 cell. (E) Luciferase activity was impaired in plasmids cotransfected with ROR1-AS1-wt and miR-504 but no change in plasmids cotransfected with ROR1-AS1-mut and miR-504. **p<0.01.