A group of highly active OK epithelial cells exhibit a variety of surface protrusions. The broad, flattened extensions that seem to roll out from the main processes of the cells like waves are called lamellipodia. Lamellipodia function primarily in locomotion and display a complex form of behavior called ruffling involving cycles of extension and contraction and an overall rearward movement toward the posterior of a migrating cell. During the high speed playback of time-lapse sequences, ruffling often produces a sensation similar to a flickering light.

Filopodia are the small, narrow protrusions that can sometimes be seen jutting out of the peripheries of the opossum kidney cells. Like lamellipodia, filopodia can be utilized to aid in cell migration, but the pointy protrusions can also be used in a sensory capacity. Filopodia can reach out over significant distances and provide information to the cell to which they belong about nearby cells or the culture environment in general. Studies have found that filopodia of adjacent cells in an epithelial sheet prompt the establishment of specialized junctions between the cells.

A third type of surface protrusion exhibited by the cells is called a bleb. Small, hemispherical mounds, blebs are most commonly observed among newly formed daughter cells. The dynamics of the blebs often give the impression that the surface of such a cell is briefly boiling. As daughter cells become settled on a substratum, the blebbing of their surfaces usually quickly subsides and wide rims of flattened lamellipodia are often extended.