Migrating OK epithelial cells usually exhibit flurried lamellipodial activity along their leading margins. The complex movement of lamellipodia, which involves cycles of extension and contraction, is known as ruffling. Though the behavior of lamellipodia can seem erratic, the overall movement of membrane ruffles is rearward. Notice, the overlapping margins of cells in the growing colony featured in the video do not exhibit ruffling. The behavior is only displayed by the free edges of cells.

Cultured epithelial cells typically experience strong contact inhibition of migration. As demonstrated by the OK cells, when epithelial cells collide, they tend to adhere to one another along shared margins, where surface extension activity has ceased. Sometimes, the continued lamellipodia ruffling along the free margins of the cells allows them to eventually sever their bonds and continue independent travels along the substratum. Often, however, the cells remain tethered together as part of a growing colony, several of which may join together to form an epithelial sheet.

A long, thin tail-like structure, termed a retraction fiber, can be observed trailing behind many actively migrating opossum kidney cells. The adhesive strands possess contractile properties. Sporadically the connections they form with the substratum are released through a poorly understood mechanism and the retraction fibers contract back into the main process of the cell to which they belong. When this occurs, there is also typically a corresponding bout of heavy lamellipodial action along the anterior margin of the cell.