The objectives of this study were to investigate the early response to mechanical stress in neonatal rat mandibular chondrocytes by proteomic analysis.To evaluate its molecular mechanism,chondrocytes were isolated and cultured in vitro,then loaded mechanical stress by four-point bending system on different patterns.Morphological observation,flow cytometric analysis,and MTT assays indicated that 4,000mstrain loading for 60 min was an appropriate mechanical stimulus for the following proteome analysis,which produced a transient but obvious inhibitory effect on the cell cycle.