SDS-PAGE and size-exclusion HPLC. (a) SDS-PAGE analysis on a 4% to 20% Tris HCl gradient mini-gel stained with Coomassie Brilliant Blue of trastuzumab (lane 1), trastuzumab Fab (lane 2), and DOTA-trastuzumab Fab (lane 3) under non-reducing conditions or these same proteins under reducing conditions (lanes 4 to 6, respectively). Molecular weight markers are shown (lane MW). The positions of 150, 50, and 25 kDa markers are indicated. Size-exclusion HPLC analyses of (b) 111In-DOTA-trastuzumab Fab (top panel) and (c) 64Cu-DOTA-trastuzumab Fab (bottom panel) with detection of absorbance at 280 nm or radioactivity.