PHF1 and Alzheimer disease: Staining of 3xTg-AD brains with anti-phosphorylated (CP13, PHF1) and conformational (MC1) tau antibodies show abundant tau accumulation in soma and axons of neurons in the hippocampus (CA1, CA2, CA3, DG), amygdala and cortex (parietal, auditory and entorrhinal cortices) (Fig. 4A).