PHF1 and Alzheimer disease: Immunoprecipitated fractions were obtained from frontal cortex homogenates of 10 advanced sporadic AD cases (n = 5 APOEε3/ε3 and n = 5 APOEε4/ε4 cases), using anti-pTau PHF1 (IPPHF1) or control IgG (IPIgG ctrl) antibodies.