Inhibition of cell migration with synthetic peptides

A method of inhibiting the invasion cells, particularly malignant cells through an extracellular membrane by contacting the membrane-cell interface with synthetic Arg-Gly-Asp-containing peptides. In one embodiment, the invention provides peptides containing the amino acid sequence Arg-Gly-Asp-Thr, more specifically Gly-­Arg-Gly-Asp-Thr-Pro, which inhibits the attachment of cells to type I collagen in addition to fibronectin and vitronectin, and a method of inhibiting the attachment of cells to type I collagen. The invention further provides an assay for quantitating the invasive quality of cells by determining the amount of such peptides necessary to prevent the cells from penetrating an extracellular membrane, such as an amniotic membrane, in vitro.