Actin lessons from pathogens

Salmonella typhimurium secretes proteins that co-opt the host actin cytoskeleton to induce membrane ruffling, leading to the uptake of the bacterium. New information about the biochemical activities of the Salmonella protein SipA suggests that this protein might inhibit host cell actin dynamics by competing with ADF/cofilin and gelsolin, two key proteins that promote the turnover of actin filaments.