Scatter factor (SF) causes contiguous sheets of epithelium to spread and cells to separate from each other. SF also increases the velocity, area, and reduces the circularity of individual cells. These changes are mediated in part by alterations in protein synthesis, protein phosphorylation, cytoskeletal reorganization, and cell surface components. SF has been purified from the conditioned medium of ras transformed 3T3 cells and human placenta. Sequence information suggests that SF from 3T3 cells is closely related to hepatocyte growth factor. SF is a glycoprotein, but glycosylation is not necessary for its activity. Glycosylation of target cell proteins, however, is required for SF action.