TBXT and Alzheimer disease: Besides τ phosphorylation, another way calpain activation play a role in τ‐mediated neurodegeneration is through inducing τ cleavage.160, 161, 162, 163, 164 But this cleavage might be at earlier stage of the disease since hyperphosphorylation makes τ, which normally is rapidly cleaved by the calpains,13, 165 highly resistant to calpain truncation,166, 167 so the NFTs in AD are resistant to calpain168 suggesting phosphorylation might regulate τ susceptibility to calpain.