Required for normal spindle assembly. Plays a key role in mother-centriole-dependent centriole duplication. Plays a role in DNA damage response: following DNA double strand breaks (DSBs), it is delocalized from centrosomes due to phosphorylation by atm and atr, leading to inactivate spindle assembly and delay mitotic progression (By similarity). Phosphorylation at Ser-559 by atm and atr promotes its delocalization from the centrosome and impairs its ability to promote centrosome dependent spindle assembly. Belongs to the CEP63 family.