MAPT，Microtubule-associated protein tau, appears to be enriched in axons. The MAPT gene is assigned to chromosome 17 by hybridization of a cDNA clone to flow-sorted and spot-blotted chromosomes and to 17q21 by in situ hybridization, containing 16 exons. The tau proteins are the product of alternative splicingfrom a single gene that in humans is designated MAPT. Tau proteins are proteins that stabilize microtubules. They are abundant in neurons in the central nervous system and are less common elsewhere. When tau proteins are defective, and no longer stabilize microtubules properly, they can result in dementias such as Alzheimer's disease.