So it turns out that phospholipids in general can move at a rate of about 1 μm squared per second. So that basically means every single second, that phospholipid can move 1 μm along that membrane. So, once again, these phospholipids generally move with a uniform constant value at a rate of about 1 μm squared per second. Now, what about proteins? Well, unlike these phospholipids, which basically move at a relatively uniform rate of 1 μm squared per second, proteins basically vary in the rate of movement. Some are immobile, they move very slowly, while others basically move very quickly and so are mobile.