Objective: To examine the role of c-Jun N-terminal kinase(JNK)in proliferation and bone-specific transcription factor runt-related transcription factor 2 (Runx2 ) mRNA expression stimulated by the serum of Zuogui pill in MC3T3-E1 osteoblastic cells. Method: We used model of MC3T3-E1 osteoblastic cells cultured in different serums with or without specific inhibitors of JNK SP 600125 within 48 hours. Grouping:control group

SP 600125 group

Zuogui pill group

Zuogui pill plus SP 600125 group

premarin group

premarin plus SP600125 group. We investigated proliferation using thiazolyl blue(MTT)assay. We analyzed JNK

and p-JNK by immunoblotting. We examined Runx2 mRNA expression in MC3T3-E1 osteoblastic cells by Real Time RT-PCR. Result: Compared with the control group

Zuogui pill group was found to stimulate proliferation significantly

the expression of p-JNK protein and Runx2 mRNA of the Zuogui pill group were increased significantly(P<0.01). SP 600125 decreased the proliferation and expression of p-JNK induced by Zuogui pill (P<0.01)

while the expression of Runx2 mRNA was not altered significantly. Conclusion: JNK signaling pathway may be involved in the proliferation induced by Zuogui pill in MC3T3-E1 osteoblastic cells

while Runx2 mRNA expression induced by Zuogui pill was independent of JNK signaling.