In high-CD44v6-expressing A431 tumours, this decrease was also significant between 48 and 72 h p.i. At 6 h p.i., the activity of 125I-Fab in the moderate-CD44v6-expressing tumours was 1.1 ± 0.6 %ID/g, steadily decreasing over time, reaching 0.25 ± 0.07 %ID/g at 72 h p.i. In the high-CD44v6-expressing A431 tumours, the activity of 125I-Fab was 1.6 ± 0.1 %ID/g at 6 h, decreasing to 0.22 ± 0.03 %ID/g at 72 h p.i. As for the 111In conjugate, the organ with the highest activity was the kidney (6.5 ± 2.1 %ID/g at 6 h), with the activity rapidly decreasing to 1.4 ± 0.2 at 24 h. This evidence concerns the gene FANCB and neoplasm.