The expression of heat shock protein 70 (hsp70) and the polymerization of the actin cytoskeleton of human umbilical vein endothelial cells (HUVECs) were investigated with the endothelial cell-extracellular matrix system and the laminar flow chamber appratus. Shear stress-induced polymerization of the actin cytoskeleton of HUVEC was summarized with the formation of the ‘dense peripheral band’ after 5 min exposure of flow, shear-induced focal contact formation at the proximal periphery, and the aligned actin microfilament formation to the direction of flow. In contrast to the intranucleous expression of hsp70 with the conventioanl heat shock, perinuclear expression of hsp70 was detected with the laser scanning confocal microscope and the western blotting of HUVECs exposed to 15 dyne/cm2 shear stress for 1 hour. Expression of hsp70 in perinuclear region increased with proportional to the magnitude of shear stress. The polymerization of cytoplasmic actin cytoskeleton and the cytoplasmic expression of hsp70 may prevent the cellular damage from the pathophysiological stimulus that initiate vascular cell disease, such as the atherosclerosis. Consequently, three-dimensional intracellular expression and the localization of protein and organelles play an important role in the signal transduction generated by the mechanical cue, such as fluid shear stress.