Evaluation of the insoluble fractions extracted from transfected cells with RD3 and anti-4R antibodies also showed that the tau seeds derived from human tauopathies caused isoform-specific seeded tau aggregation in the presence of both 3R tau and 4R tau substrates, except for the accumulation of insoluble 4R tau induced by the unpurified PiD-2 seeds (Fig. 4B and Supplementary Fig. 5). This evidence concerns the gene MAPT and tauopathy.