Aim Phosphorylation and nuclear translocation of extracellular signalregulated kinases(ERK1/2) are most important for proliferation of oxidativestressed vascular smooth muscle cells(VSMC) and heat shock protein 90(HSP90) is involved in this process.We investigate whether heat shock protein 90 participated in extracellular signal-regulated kinases 1/2 pathway as a molecular chaperon. Methods Exposure vascular smooth muscle cells to LY83583(6-Anilinoquinoline-5,8-quinolinedione,produce reactive oxygen species,1 μmol/L) for different time,then heat shock protein 90,extracellular signal-regulated kinases 1/2 and phospho-extracellular signal-regulated kinases 1/2 in cell lysates were measured by western blot.Vascular smooth muscle cells were incubated with geldanamycin (a special inhibitor of heat shock protein 90,5 μmol/L) or vehicle for 30 min,then with LY83583(1 μmol/L) for 120 min,heat shock protein 90 binding with extracellular signal-regulated kinases 1/2 and phospho-extracellular signal-regulated kinases 1/2 were quatified by immunoprecipitation and western blot.The nuclear translocation of phospho-extracellular signal-regulated kinases 1/2 were measured by immunofluorenscense. Results Heat shock protein 90 increased in a time-dependent manner.It got the peak at 120 min which corresponded to the second peak of phospho-extracellular signal-regulated kinases 1/2.Immunoprecipitation and western blot analysis showed that LY83583 increased the complex of heat shock protein 90-phospho-extracellular signal-regulated kinases 1/2 about 5.5 times(p<0.01) vs control,and phospho-extracellular signal-regulated kinases 1/2 in total cell lysis(about 6.1 times vs control,p<0.01) and nuclear increased too.Geldanamycin attenuated the effect of LY83583. Conclusions Heat shock protein 90 bound with phospho-extracellular signal-regulated kinases 1/2 and promoted their nuclear translocation in oxidative-stressed vascular smooth muscle cells.