Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia axoneme (PubMed:36191189). Important for proper ciliary and flagellar beating. May act in cooperation with CFAP45 and axonemal dynein subunit DNAH11 (PubMed:33139725). May play a role in cell growth and/or survival (PubMed:15967112). {ECO:0000250|UniProtKB:E1BKF9, ECO:0000269|PubMed:15967112, ECO:0000269|PubMed:33139725, ECO:0000269|PubMed:36191189}. This is the function of ENSG00000166596 (CFAP52, cilia and flagella associated protein 52).