Possible models for the bi-directional movement observed in the dynein-dynactin molecular motor along microtubules. A) Some
movements may be due to random, diffusive motions; B) Some of the movements may be due to a flexible rotation of the dynein ring; and C) Some of the movement may be dictated by the microtubule lattice itself.

Image Credit: Jennifer L. Ross, PhD, University of Pennsylvania School of Medicine; Nature Cell Biology