Plays a role in microtubule (MT) stabilization and this stabilization involves the maintenance of NUMA1 at the spindle poles. Colocalizes with polyglutamylated MTs to promote MT stabilization and regulate bipolar spindle formation in mitosis. Binding of CCSAP to centrosomes and the spindle around centrosomes during mitosis inhibits MT depolymerization, thereby stabilizing the mitotic spindle (PubMed:26562023). May play a role in embryonic development. May be required for proper cilia beating (By similarity). . This is the function of ENSG00000154429 (CCSAP, centriole, cilia and spindle associated protein).