Contact often inhibits the migration of U2OS epithelial cells. In culture, repeated collisions cause the cells to form small colonies, which eventually develop into continuous sheets similar to the epithelial sheets that occur in the animal body. A number of cell-cell junctions form between epithelial cells, including tight junctions, which are a special type of connection unique to the cell type. Other junctions that may hold two U2OS or other epithelial cells together are adherens, desmosome, gap, and hemidesmosome junctions.

At any given moment, cells viewed under a microscope may seem as if they were static entities. Time-lapse studies, however, reveal a very different picture, cells and the organelles they contain proving to be extremely dynamic. The movement of mitochondria and other organelles, which can be observed during the high speed playback of this time-lapse sequence, occurs in saltations, episodic jumps interrupted by periods of rest. In cells thoroughly settled on a substratum, saltatory movement is typically directed either toward or away from the central region of a cell, usually in association with the intracellular microtubule network.

The formation and retraction of a variety of surface protrusions can be observed during the video of live U2OS human osteosarcoma cells. The broad, flattened extensions around the peripheries of the cells are lamellipodia. The activity of lamellipodia is generally most pronounced along the leading margin of a migrating cell. Filopodia are the small, narrow projections that can be observed sporadically jutting from the surfaces of the cells. Filopodia can function in locomotion and in the sensory capabilities of a cell. Following cell division, a third type of protrusion, called a bleb, can frequently be seen. Blebs are small, dynamic hemispherical mounds that can give a cell the appearance that its surface is boiling when they form and recede.