Madin-Darby bovine kidney cells locomote primarily through the extension and contraction of broad, fan-shaped lamellipodia. Each time one of the surface extensions is formed or drawn back, cytoplasmic streaming occurs. In the central region of the cell the cytoplasm is fluid-like and is commonly referred to as plasmasol. At the periphery of lamellipodia, however, the cytoplasm exhibits the consistency of a gel and is called plasmagel. When a lamellipodium is extended, plasmasol flows into the surface structure, transforming into plasmagel as it fills in the space around the margin of the growing extension. The reverse of this process occurs during retraction; plasmagel along the edge of the lamellipodium liquefies and streams back into the center of the cell.

MDBK cells, as well as many other types of epithelial cells, are contact inhibited in culture. When two of the bovine kidney cells collide, the activity of their lamellipodia (termed ruffling) largely ceases in the area of overlap and the cells adhere to one another. Sometimes the cells will eventually break apart and begin to travel in new directions, but more often they remain connected to one another, resulting in the formation of small colonies. Over time, many colonies in culture may come together to form sheets of cells, similar to the epithelial sheets they form in the body.

The division of several different MDBK cells can be observed during the course of this short time-lapse sequence. Immediately prior to the process, the cells retract their surface projections and assume a roughly spherical form. When the sphere-shaped cells divide, the new daughter cells seem to bubble wildly for a brief period of time as small mounds called blebs contort their surfaces. Eventually the blebs, which are remnants of the spherical cell form, completely subside as the daughter cells settle on the substratum and extend flattened lamellipodia across the culture medium.