Objective To elucidate the mechanotransduction pathways and gene expression in osteoblasts in response to fluid-induced shear stress in hope to be applied in tissue engineering.Methods Osteoblastic MG63 cells were exposed to shear stress of 12 dynes/cm2 for the designated times and their activations of MAPK(i.e., ERK,JNK,and P38)were examined by western blotting.The expressions of bone formation-related genes,in- cluding COX-2,Egr-1,c-fos,and OPN,were detected by RT-PCR.Results We found that shear stress induced phosphorylation of ERK,JNK,and P38 MAPK,and expressions of bone formation-related genes,including COX-2, Egr-1,c-los,and OPN.Conclusions Shear stress can turn on the signal transduetion and enhance bone forma- tion-related gene expression in osteoblasts.This phenomenon may imply that shear stress can be applied in tissue engineering.