Tubulin is the major constituent of microtubules. Microtubules are assembled from dimers of α- and β-tubulin. α-Tubulin cleaved by caspase-6 can be found in neurons, neurofibrillary tangles, neutrophil threads, and neuritic plaques in Alzheimer disease. α-Tubulin has been found to associate with the axonal microtubule-associated protein Tau, indicating that the cleavage of the functional α-Tubulin C-terminal domain by caspase-6 could alter the state of microtubules in neurons.