A speculative model for the mode shift of centriole engagement. Centriole engagement in interphase is maintained cooperatively by Cep57 and Cep57L1, and Plk1 changes the engagement mode to a Cep57- and PCNT-dependent one at the mitotic entry. Cep57/Cep57L1 codepletion induces precocious centriole disengagement during interphase, and such disengaged daughter centrioles are converted into centrosomes and can reduplicate before entering mitosis. Consequently, the centriole number increases, which results in the high frequency of chromosome segregation errors.