Before revision:  A DP diffuses or walks along a MT to reach one of the tips of the MT andthen begins depolymerizing the MT itself .
After revision:  A DP diffuses or walks along a MT to reach one of the tips of the surface of a microtubule, depolymerases are transported to the microtubule tip(s) by diffusion or directed walk and, then, depolymerize the microtubule from the tip(s) after accumulating there .