Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 52 10 2014 10 15 728 733 EN Shabnam Yazdian Department of Toxicology & Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. Najmeh Fahham Department of Pharmacology, Iran Pasteur Institute, Tehran, Iran. Mohammad Hossein Ghahremani Department of Toxicology & Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. Monireh Afzali Virtual School, Tehran University of Medical Sciences, Tehran, Iran. Narges Farsandaj Department of Toxicology & Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. Melody Vatankhah Department of Biology, College of Science, University of Tehran, Tehran, Iran. Seyed Nasser Ostad Department of Toxicology and Pharmacology, Toxicology and Poisoning Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 11 There is a great concern about the effect of propoxur, as one of the more common N-methyl carbamate pesticides, on human health due to its extensive use in agricultural and non-agricultural applications. Caco-2 cells became resistant to propoxur, and the resistance was confirmed through MTT assay. Then the cell membrane integrity and P-glycoprotein expression were measured by LDH assay and western blot analysis, respectively and compared to the parent cells.  Contrary to what was expected, the expression of P-glycoprotein in propoxur resistant cells was lower than parent cells.This study indicates that the resistance to propoxur may not be related to P-glycoprotein expression directly, since P-glycoprotein expression has decreased in these cells. https://acta.tums.ac.ir/index.php/acta/article/view/4557 https://acta.tums.ac.ir/index.php/acta/article/download/4557/4639