Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia axoneme, which is required for motile cilia beating. Interacts with MYH9 (PubMed:28345668). Interacts with MYH10 (PubMed:28345668). Expressed in undifferentiated embryonic stem cells. Down-regulated following embryonic stem cells differentiation.