Negatively regulates cilia formation by recruiting the CP110-CEP97 complex (a negative regulator of ciliogenesis) at the distal end of the mother centriole in ciliary cells (PubMed:30375385). At the beginning of cilia formation, MPHOSPH9 undergoes TTBK2-mediated phosphorylation and degradation via the ubiquitin-proteasome system and removes itself and the CP110-CEP97 complex from the distal end of the mother centriole, which subsequently promotes cilia formation (PubMed:30375385).
