Tumour-to-organ ratios of (A) 111In-Fab and (B) 125I-Fab in tumours and organs of SCC tumour-bearing mice. A431 tumours were used as reference for tumour-to-organ ratio calculations. The animals were sacrificed at 6 h (black bars), 24 h (dark grey), 48 h (light grey) and 72 h (white) post injection. Inset: tumour-to-blood ratios of radiolabelled Fab for both A431 and H314 tumours. Error bars represent SD (N = 5).