Serine/threonine-protein kinase PLK4 (PLK4)

Able to trigger procentriole formation on the surface of the parental centriole cylinder, leading to the recruitment of centriole biogenesis proteins such as SASS6, CENPJ/CPAP, CCP110, CEP135 and gamma-tubulin. When overexpressed, it is able to induce centrosome amplification during the simultaneous generation of multiple procentrioles adjoining each parental centriole during S phase.

Phosphorylates 'Ser-151' of FBXW5 during the G1/S transition, leading to inhibit FBXW5 ability to ubiquitinate SASS6. Its central role in centriole replication indicates a possible role in tumorigenesis, centrosome aberrations being frequently observed in tumors.