Fig 1: There is no significant change in tau kinase and phosphatase activities by fisetin treatment.(a) Mouse cortical cells (T4) were treated with either DMSO (Veh) or 5 μM fisetin (FST) for 12 h. Tau kinase assay was performed according to Methods. The levels of tau phosphorylated at Ser262 and Ser396/Ser404 were analyzed by immunoblotting using a 12E8- and PHF1-specific antibody, respectively. GST-tau was detected with a total tau antibody. (b) Bar graph of the relative optical density of phosphorylated tau normalized to actin. Data shown are mean ± SE and were analyzed using Student’s t test. (c) The phosphatase activity of PP2A in cell lysates was quantitated using the Serine/Threonine Phosphatase Assay System (Promega) by measuring the dephosphorylation of a phospho-peptide, RRA(pT)VA in the presence or absence of okadaic acid (OA, 20 nM). Data shown are mean ± SE of three independent experiments and were analyzed using Student’s t test. n.s. means data are not significant.