Microtubule-associated protein involved in mitotic spindle formation. Forms a dimer (By similarity). Binds to microtubules (MT). Bundles polymerized MT via the formation of 25-nm crossbridges with centrally located endocytic MT. Localized specifically to MT that rearranged to form a spindle and the polar sides of the spindle proper. Associates to MT in preprophase band, during anaphase, and in phragmoplast. Cell cycle-regulated expression with higher levels during mitosis. Belongs to the MAP65/ASE1 family.