Western blot analysis of homogenates of brain (B) and spinal cord (S) of Tg30tau and wild-type mice at 3, 6, and 12 months of age. Equivalent protein yields (100 μg) were loaded in each lane. A: M19G human-specific tau antibody. The human transgenic tau protein is present at all ages inTg30 mice (and not in wild-type) as a 64-kd species but a slower migrating species of 69 kd is also detected at low level at 3 months and at higher level in 6- and 12-month-old Tg30tau mice. B: AD2 phosphotau antibody. The antibody detects both the 64- and the 69-kd species in Tg30tau mice, already at 3 months. C: AT8 phosphotau antibody. The antibody detects only the 69-kd species, a strong signal being first seen at 6 months in the spinal cord. D: AT100 conformation-dependent phosphotau antibody. The antibody detects only the 69-kd species, already at 3 months and in both the brain and the spinal cord. E: Actin antibody, used as a control for protein loading. The numbers on the left refers to the positions of PHF-tau proteins of 69 and 64 kd.