Further similar clinical applied probes include cathepsin/MMP-sensitive poly-lysine-based near-infrared fluorescence (NIRF) probes [149,150] for the early and effective detection of cancers of the gastrointestinal tract [151] and pan-cathepsin-sensitive PEG-based probe for the detection of STS and breast cancer [129,152]. The gene discussed is CTSS; the disease is breast cancer.