Objective       To determine the effect of fibroblast growth factor 2 (FGF2) on the differentiation of bone marrow monocytes (BMMCs) to osteoclast and bone resorption function.       Methods       After BMMCs were isolated from the bone marrow of femurs and tibiae from C3H mice

the cells were treated with receptor activator of nuclear factor-kappa B ligan

d (RANKL) and macrophage colony stimulating factor (M-CSF). Experimental and control groups were separated by addition of FGF2 or not. The differentiation and maturation of osteoclast precursors were observed by TRAP staining

and the osteoclast actin ring of both group were analyzed by phallodine staining. The expression of Trap

Mmp9

Ctsk and Clcn7 at mRNA level were detected by real-time PCR. The function of bone resorption was measured by bovine bone slice and osteoclast coculture. The effect of FGF2 on activity of ERK protein in the osteoclasts was analyzed by Western blotting.       Results       There was no significant difference in differentiation and maturation of osteoclast precursors between 2 groups (

P

0.05)

neither in the actin ring of osteoclasts. The mRNA expression level of Trap

Mmp9

and Ctsk were upregulated after FGF2 treatment (

P

0.05)

however

Clcn7 mRNA expression level was not influenced. Compared with control group

the bone resorption lacuna area of FGF2 treated group was larger (

P

0.05). Finally

Western blot analysis showed that treatment with FGF2 induced enhanced activity of phosphorylated ERK in cultured osteoclasts.       Conclusion       FGF2 cannot influence the differentiation of osteoclast precursors or formation of actin ring

but can upregulate the function of osteoclastic resorption via an ERK-related pathway.