OBJECTIVE To address whether matrix Gla protein (MGP) can inhibit mineralization in normal rat kidney tubular cells (NRK-52E) under high concentration of calcium. MATERIALS AND METHODS NRK-52E cells were treated with high concentration of calcium. The viability and apoptosis of cells were detected by cell counting kit-8 and flow cytology, respectively. Real-time-polymerase chain, Western blotting, and immunofluorescence analysis were conducted to detect the expression of MGP. Cells were transfected with plasmid-MGP or siRNA-MGP for up- or down-regulation of the expression of MGP, respectively. Rat recombinant MGP was also used as supplementation of exogenous MGP. Alizarin red staining was conducted to detect the adherent and deposition of calcium salt. RESULTS High concentration of calcium suppressed MGP expression in NRK-52E cells. There was significant mineralization when NRK-52E cells were treated with high concentration of calcium. Supplementation with exogenous rat recombinant MGP and overexpression of endogenous MGP both decreased the adherent and deposition of calcium salt to NRK-52E cells, while silence of MGP showed reverse results. CONCLUSION MGP plays an inhibitory role in the stone formation. However, high concentration of calcium significantly inhibits the expression of MGP and then promotes mineralization in NRK-52E cells. (C) 2018 Elsevier Inc.