MAPT and tauopathy: To determine whether the tau phosphorylation pattern is recapitulated in neuronal cells and potentially contributes to tau pathology, we quantified tau level by the immunofluorescence using HT7 antibody for total tau, and PHF1 (detecting pSer396 and pSer404 tau; Figure 2a) and AT8 (detecting pSer202 and pSer205 tau; Figure S3a) antibodies for phosphorylated tau in SH‐SY5Y P301L cells, as tau hyperphosphorylation at these sites has been shown as pathogenic markers in related tauopathies (de Calignon et al., 2012; Espuny‐Camacho et al., 2017; Stratmann et al., 2016).