Fig. 4.

OA induces tau hyperphosphorylation with nuclear Ca²⁺/CaMKIV upregulation. A, B HEK293 cells with stable expression of human wild-type tau (293Tau) were treated with OA (10 nmol/L) for 12 h, and the increased phosphorylation level of tau at Thr204, Ser214, Thr231, Ser396, and Ser404 was detected in the nuclear fraction by Western blotting (Tau5 probes total tau proteins). C, D OA treatment further increased pCaMKIV in the nuclear fraction. E OA treatment further increased nuclear [Ca²⁺]. Data are expressed as mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 vs OA.