Figure 3. NIRF imaging 24 hours after intravenous injection of the cathepsin-B-sensitive autoquenched probe in a representative animal. A, light image; B, raw NIRF image; and C, color encoded NIRF signal (arbitrary units of NIRF intensity) superimposed on light image. The highly invasive breast adenocarcinoma (DU4475) was implanted on the right of the chest and the well differentiated adenocarcinoma (BT20) on the left. Note the higher fluorescent signal depicted on the highly invasive breast lesion (B, C).