MAPT and tauopathy: Likewise, cofilin-S3A-mRFP but not cofilin-S3E-mRFP expression in Tau-P301S;cofilin+/− mice reverted phospho-tau (pS199/pS202) to Tau-P301S levels (Fig. 7e, f), indicating again that “active” but not “inactive” cofilin mediates Tau-P301S-induced tauopathy.