Aim To investigate the effect of angiotensin Ⅱ(AngⅡ) on cysteine-rich 61(Cyr61) expression and its transduction access in cultured rat vascular smooth muscle cells(VSMC).Methods VSMC were cultured in sticking mass methods.VSMC were treated with AngⅡfor 15 min,30 min,60 min,180 min,which were pretreated with PD98059 for 60 min before AngⅡ treatment.The Cyr61 expression in VSMC were characterized by reverse transcription polymerase chain reaction(RT-PCR) and Western blotting.Results RT-PCR analysis revealed that Cyr61 increased in cells treated with 1 μmol/L AngⅡ for 15,30 min compared with control(p<0.01) and still expressed at 60 min and attenuated at 180 min.Phosphorylated extracellular signal regulated kinase(P-ERK) 1/2 activity increased in cells treated with 1 μmol/L AngⅡ for 30 min compared with control(p<0.01),Cyr61 expression and P-ERK1/2 activity were inhibited by the presence of 20 μmol/L PD98059,a specific inhibitor of ERK1/2.Conclusions AngⅡup-regulates Cyr61 expression in cultured rat VSMC via ERK1/2.This may be a significant mechanism for VSMC proliferation by AngⅡ.