Cortical NuMA is essential for regulating spindle orientation and recruiting dynein/dynactin to the cell cortex. NuMA stability and spindle orientation activity require interactions with 4.1 family proteins in metaphase. In anaphase, loss of NuMA phosphorylation results in its cortical association in an LGN- and 4.1-independent manner.

Differentiation induces loss of centrosomal microtubule organizing activity in many cell types, though the underlying mechanisms are poorly understood. Using the epidermis, Muroyama et al. show that cell cycle exit causes loss of a Nedd1–γ-tubulin complex, which is required for anchoring microtubules at the centrosome. This defines a novel function for γ-tubulin complexes in microtubule anchoring at the centrosome.