Analysis by immunoblotting of early Aβ deposition in Tg2576 brain. Aβ in the SDS (A,C) and formic acid (B, D) extracts from 4–10 month Tg2576 brains was analyzed on immunoblots labeled with BAN-50 (anti-Aβ1–16) (A,B) and 4G8 (anti-Aβ17–24) (C,D). Proteins were separated on 10–20% Tricine gels, and each lane shows the Aβ in 40 μl of the formic acid or SDS extract as described in Materials and Methods. Immunoblotting was first performed with BAN-50. The blots were then stripped and reblotted with 4G8. Note that SDS-soluble Aβ decreases transiently at 8 months, when SDS-resistant, formic acid-soluble Aβ appears. The arrows identify CTFβ, and thearrowheads identify Aβ.