Abstract
Within 30 minutes of exposure to medium containing 10% dimethyl sulfoxide, PtK2 cells begin to round up and lose their cytoplasmic actin bundles. At the same time, bundles of actin filaments appear in the nuclei of the cells. One to 2 hours after the dimethyl sulfoxide is removed from the medium, the cells revert to their flattened shape, losing the nuclear actin bundles and regaining the cytoplasmic bundles.