Essential for the formation and stability of microtubules (MTs) (By similarity). Required for the organization of the mitotic spindle and for the proper attachment of kinetochores to MTs (By similarity). Promotes the recruitment of NUDC to the mitotic spindle for mitotic progression (By similarity). Homotrimer; self-association is mediated by the N-terminal coiled coil. Localizes to microtubules (MTs) during interphase with a significantly reduced affinity for MTs during mitosis. Belongs to the WD repeat EMAP family.