For instance, in human tauopathies, the filaments in different diseases are composed of different tau isoforms.24,25 In familial tauopathies, incorporation of WT tau vs. mutant tau into filaments is mutation dependent.25 We therefore explored the efficacy of WT 0N4R tau-RING in removing pre-existing aggregates in TVA cells, which carry the P301S mutation. Here, MAPT is linked to tauopathy.