If kinesin is the outbound train, dynein runs inbound. It marches on microtubules from a cell’s periphery toward its center. The motor protein is essential to cell survival, driving such activities as organelle transport and centrosome assembly. Dynein has a sizeable wheel-like motor domain that binds multiple ATPs and has a complex tail region to connect to cargo. The molecule is much bigger than kinesin—the distance between dynein’s ATP-binding site and its feet is four times the size of the whole kinesin molecule. Animation by Janet Iwasa in collaboration with the Reck-Peterson lab.