- Cytotoxic necrotizing factor type 2 produced by virulent Escherichia coli modifies the small GTP-binding proteins Rho involved in assembly of actin stress fibers. Oswald, E., Sugai, M., Labigne, A., Wu, H.C., Fiorentini, C., Boquet, P., O'Brien, A.D. Proc. Natl. Acad. Sci. U.S.A. (1994)