APP and Alzheimer disease: Caccamo et al. [6] reported that the 3XTg-AD amyloid model [42], which express mutant amyloid precursor protein, mutant presenilin 1, and P301L mutant tau protein, have increased full-length and ~35 kDa TDP in the low salt fraction and cytosolic fraction at 6 months of age, but not at 2 months or 12 months.