Vimentin enhances the catalytic activity of hGIIA. hGIIA (0.1 μg/mL) was incubated with vimentin or rod-vimentin immobilized to the bottom of 96-well microtiter Costar plates or was directly coated to the bottom of the polystyrene wells. In controls, untreated wells were precoated with 5% milk proteins prior to incubation with hGIIA. Catalytic activity was monitored using the PED6 fluorescent phospholipid analog as described in “Materials and methods.”