ObjectiveTo study the effect of fluorine on proliferation of osteoblast through extra cellular signal-regulated protein kinase(ERK) signaling pathway.MethodsMouse osteoblasts(MC3T3-E1) were cultured in vitro with different concentrations of fluoride for 24 and 48 h (the concentrations of Fˉ were 0,200,400,600,1000,2000,4000,8000,10 000 μmol/L,respectively).The optimum concentration for promotion of cell proliferation was determined by methylthiophene tetrazolium(MTT) assay.According to the optimum concentration,the cells were randomly divided into three groups:control group (0 μmol/L Fˉ); fluorine group (400 μmol/L Fˉ); fluorine and MAPK inhibitor PD98059 group(400 μ mol/L Fˉ + 10 μ mmol/L PD98059).Cell cycle was detected by flow cytometry after 48 h culture.The expression of P-ERK protein was determined by Western blotting and immunofluorescence.ResultsThe optimum concentration of fluorine for proliferation of osteoblasts was 400 μ mol/L.Compared with the control group[(76.12 ± 10.08)％,(2.06 ± 0.31)％],the number of cells in G0/G1 phase[(63.04 ± 8.12)％] reduced and the number of cells in S phase[(9.13 ± 2.08)％] increased in fluorine group (all P ＜ 0.05) ; but the number of cells in G0/G1 phase [(92.11 ± 9.01 ) ％] in fluorine and mitogen-activated protein kinases (MAPK) inhibitor PD98059 group was significantly increased(P ＜ 0.05 ).Western blotting results showed that:compared with the control group[(100.00 ± 0.00)％],the expression of P-ERK protein in fluorine group[(131.24 ± 13.88)％] was significantly higher(P ＜ 0.05 ),but the expression of P-ERK protein in fluorine and MAPK inhibitor PD98059 group [(91.33 ± 9.68 )％] was not significantly changed(P ＞ 0.05).The results of immunofluorescence were similar to that of Western blotting.ConclusionsFluorine at the concentration of 400 μmol/L can promote the proliferation of osteoblasts.ERK signaling pathway has played a key role in the proliferation of osteoblasts.