Now, some proteins move relatively quickly while other proteins are essentially immobile. Why? Well, because some proteins, like this one here isn't actually physically attached onto any other molecule or any other structure. But other transmembrane proteins or integral proteins are basically attached onto physical structures. For instance, in this case, it's attached not only onto the collagen fibers of the extracellular matrix found outside the cell but they're also attached onto the filaments in the cytoskeleton found in the cytoplasm inside of that cell. So this one will be relatively mobile while this protein will be able to move along that lateral direction.