Involved in mitotic spindle regulation and coordination of mitotic processes. The function in regulating microtubule dynamics at spindle poles including spindle orientation, astral microtubule density and poleward microtubule flux seems to depend on the association with the katanin complex formed by KATNA1 and KATNB1. Enhances the microtubule lattice severing activity of KATNA1 by recruiting the katanin complex to microtubules. Can block microtubule minus-end growth and reversely this function can be enhanced by the katanin complex (PubMed:28436967). May have a preferential role in regulating neurogenesis. {ECO:0000269|PubMed:12355089, ECO:0000269|PubMed:15972725, ECO:0000269|PubMed:28436967}. This is the function of ENSG00000066279 (ASPM, assembly factor for spindle microtubules).