en Clinical Biochemistry Clinical Biochemistry Original Article Original Article <span style="font-family:Tahoma;"><span style="font-size:12px;"><span style="unicode-bidi:embed"><span style="line-height:107%">Caveolin-1(Cav-1) is one of the most important components of caveolae in the cell membrane, which plays an important role in cell signaling transduction, such as EGFR and TGF-&beta; receptor transactivation. The purpose of this study was to evaluate the effect of c-Abl and NAD(P)H oxidases (NOX) on phosphorylation of Cav-1 and consequently their effect on phosphorylation of Smad2C induced by Endothelin-1 in human vascular smooth muscle cells (VSMCs). In this study, all experiments were performed using human VSMCs. The phosphorylation level of the Caveolin-1 and Smad2C proteins were assessed by western blotting using Phospho-Caveolin-1 (Tyr14) antibody and phospho-Smad2 (Ser465/467) antibody. The data were reported as mean &plusmn; SEM. The VSMCs treated with endothelin-1(ET-1) (100 nanomolar (nmol)) demonstrated a time-dependent increase in the pCav-1 level (p<0.05). The inhibitors of NOX (diphenyleneiodonium) (p<0.05), cholesterol depleting agent (beta-cyclodextrin) (p<0.05) and c-Abl inhibitor (PP1) (p<0.01) were able to reduce the level of the phospho-Cav-1 and phospho-Smad2C induced by Et-1 (p<0.05). Our results proposed that caveolae structure, NOX, c-Abl played an important role in the phosphorylation of Cav-1 induced by ET-1 in the human VSMCs. Furthermore, our findings showed that phosphoCav-1 involved in TGFR transactivation. Thus, Et-1 via a transactivation-dependent mechanism can cause phosphorylation of Smad2C.</span></span></span></span> Endothelin-1, Caveolin-1, c-Abl, NADPH oxidase, Smad2 protein 297 305 http://ijmcmed.org/browse.php?a_code=A-10-1167-1&slc_lang=en&sid=1 Mahsa Hosseinipour Hosseinipour23@gmaail.com 100319475328460032642 100319475328460032642 No Hyperlipidemia Research Center, Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Mojtaba Rashidi Rashidi436@gmail.com 100319475328460032643 100319475328460032643 No Hyperlipidemia Research Center, Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Faezeh Seif Seifffd12@gmail.com 100319475328460032644 100319475328460032644 No Department of Basic sciences, Shoushtar Faculty of Medical sciences, Shoushtar, Iran. Hossein Babaahmadi-Rezaei hbr.biomed@gmail.com 100319475328460032645 100319475328460032645 Yes Hyperlipidemia Research Center, Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.