Fig. 2.

Microtubules polarise spreading cells for migration and epithelial cells in the apical–basal orientation. (A) In spreading and migrating cells, microtubules are orientated from the centrosome towards the periphery (1). Plus-end-directed microtubule motors transport cargoes to the leading edge (2). Phosphorylation of CLASP1 and/or CLASP2 controls the extent of their association with microtubule plus ends (3). The Par3–aPKC–TIAM1 complex stabilises microtubules at the leading edge to allow persistent migration (4). (B) In polarised epithelia, non-centrosomal microtubules are orientated along the apical–basal axis (1). Plus-end-directed motors transport adhesion proteins and other cargoes to the basal surface (2). Known and possible interactions linking integrins with microtubules (3). Par1b and the microtubule crosslinker MTCL1 determine the balance between stable and dynamic non-centrosomal apical–basal microtubules (4).