Golgi- and centrosome-nucleated microtubules in cell migration. The centrosome nucleates a radial array of microtubules (red) whose minus ends () are anchored at the centrosome and whose plus ends (+) extend into the cell periphery. This population of microtubules depends on -TuRC complexes and the large scaffold protein AKAP450 for their nucleation and functions in maintaining the pericentriolar localization of the Golgi ribbon by a dynein-mediated mechanism (closed arrows). In contrast, the Golgi apparatus nucleates micro¬tubules (brown) that extend asymmetrically toward the leading edge of a migrating cell. Microtubule nucleation at the Golgi requires the peripheral Golgi protein GM130, which recruits AKAP450 and -TuRC complexes to the Golgi apparatus. Golgi-nucleated microtubules are coated with CLASP proteins and are necessary for the formation of the Golgi ribbon from dispersed stacks. In addition, they are required for cell migration by facilitating polarized protein transport to the leading edge of a cell (open arrows).