Microtubule-associated protein which regulates cell division and neuronal migration during cortical development. Necessary for mitotic spindle organization. Necessary for radial and tangential cell migration during brain development, possibly acting as a regulator of cell morphology and process formation during migration. May enhance calcium influx through CACNA1E and stimulate programmed cell death (By similarity). Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia axoneme, which is required for motile cilia beating (PubMed:34715025). Interacts with the C-terminus of CACNA1E. Interacts with alpha-tubulin. Expressed in trachea multiciliated cells.