To further verify that pFTAA was binding to insoluble filamentous tau, cultured DRG neurons were imaged before and after formic acid treatment, which solubilizes filamentous tau in brain sections from Alzheimer's disease patients (Bing et al., 2006) and in brain sections from P301S tau mice (Velasco et al., 2008). This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.