Missing molecule hobbles cell movement

Cells are the body's workers, and they often need to move around to do their jobs. Frequently, a cell will move through a tissue -- say, the wall of a blood vessel -- the way a rock climber scales a cliff, using a protein called integrin to grab onto a spot and pull itself in that direction. But cells missing the CD13 protein on their cell walls can't recruit integrin, and get stuck in place.