The cortical collecting duct regulates ion and water homeostasis in the kidney. A cell line denoted M-1 has been established from the cortical collecting duct of a transgenic mouse that exhibits many functional properties of the original tissue. While this cell line is valuable for in vitro studies, the cells are not easily transfected. Frequently, adenovirus-mediated gene transfer is used. As adenovirus production requires several additional steps, we prefer chemical methods to achieve recombinant protein expression in M-1 cells. Previous attempts to transfect this cell line were unsuccessful with far less than 10% of transfectants, although different reagents were tried. Here we compare three commercially available transfection reagents in terms of the percentage of transfected cells and the suitability for using a reporter construct in M-1 cells. more