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. Phosphorylation at Ser-560 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.