Centrosomal protein of 55 kDa is a protein that in humans is encoded by the CEP55 gene. CEP55 is a mitotic phosphoprotein that plays a key role in cytokinesis, the final stage of cell division. Interacts (phosphorylated on Ser-425 and Ser-428) with PLK1. Interacts with AKAP9; the interaction occurs in interphase and is lost upon mitotic entry. Interacts with PCNT; the interaction occurs in interphase and is lost upon mitotic entry. Interacts with PDCD6IP; the interaction is direct; CEP55 binds PDCD6IP in a 2:1 stoechiometry; PDCD6IP competes with TSG101 for the same binding site.