An efficient genetic screen in mammalian cultured cells.

Genetic approaches in mammalian cultured cells had limited success because the isolation of mutants and the identification of the mutated genes were often difficult. In the present report, we describe the establishment of a novel genetic screen in Cos-7 cells that allows rapid identification of polypeptides whose overexpression inhibits a certain cellular process. We demonstrate that this approach can be used successfully to isolate partial cDNAs whose overexpression specifically interfered with the clathrin-mediated endocytosis of transferrin.