PPM1D is inversely targeted by miR-499a-5p in the human MG-63 osteosarcoma cell line. (A) The predicted consequential pairing of miR-499a-5p and 3′-UTR of PPM1D mRNA. (B) Following transfection of the MG-63 cell line with an miR-499a-5p mimic in the wild-type 3′-UTR of PPM1D, the relative luciferase activity was markedly suppressed in comparison with its NC. No statistical significance was observed when the MG-63 cell line was transfected with miR-499a-5p in the mutant 3′UTR of PPM1D. Relative expression of (C) miR-499a-5p was notably upregulated and relative expression of (D) PPM1D mRNA was downregulated when MG-63 cells were transfected with an miR-499a-5p mimic. (E) Western blot analysis and (F) statistical analysis demonstrating that the relative expression of PPM1D protein was significantly downregulated by transfection of MG-63 cells with an miR-499a-5p mimic compared with the NC group. *P<0.05, **P<0.01, ***P<0.001. PPM1D, protein phosphatase 1D; UTR, untranslated region, NC, negative control; miR, microRNA.