Aim To investigate the effects of phosphatidylinositol 3-kinase (PI3K)/protein kinase C-ζ (PKC-ζ)complex on regulating angiotensin Ⅱ(AngⅡ) activation of p70 ribosomal S6 kinase (p70S6K) in vascular smooth muscle cells(VSMC). Methods VSMC isolated from 200 g to 250 g male Sprague-Dawley rats were cultured to 70% to 80% confluence and were growth-arrested by incubation in 0.1% calf serum/DMEM for 48 h before use. Both 3 H-TdR incorporation and cell counting were used to estimate the proliferation of VSMC. Western blot, immunoprecipitation and immunoblot analyses were performed to valuate the AngⅡ-stimulated kinase expression and Ras-PI3K-PKC-ζ association of VSMC. Phosphotransferase assay by using S6 peptide as substrate was employed to measure the p70 S6K activity. Results VSMC expressed p85PI3K, PKC-ζ and p70S6K; AngⅡ and PDGF stimulation did not affect the p85PI3K, PKC-ζ and p70S6K expression. 2) 100 nmol AngⅡ