Fig. 2. Polarization of the microtubule cytoskeleton in a migrating cell. (a) In many cell types, the centrosome reorients towards the direction of migration (black arrow). (b) Stable, detyrosinated microtubules (purple) appear to be oriented preferentially in the direction of migration. (c) Microtubules exhibit net growth near the leading edge and, (d) as a result of actin-dependent retrograde flow (orange arrow) buckle and break in the cell body, creating depolymerising microtubule minus ends and dynamic plus ends. (e) Microtubule plus-end-binding proteins such as APC or CLASPs might stabilize growing microtubule ends in the leading edge. In this and all subsequent figures, the open arrow indicates the direction of cell migration. Thick black lines represent microtubules. Green and red arrows indicate growing or shrinking microtubules, respectively, and plus and minus signs indicate microtubule polarity.