Table 1.

Representative activity-based probes and their application to cancer research

Structure*	Enzyme class	Applications in cancer
	Serine hydrolases	Identified increased KIAA1363 (REFS 49,52,53) and MAGL11 activities in aggressive human cancer lines11,52 and primary tumours11,49. Identified increased uPA and tPA serine protease activities in secreted proteomes of aggressive cancer cells51,52. Identified increased RBBP9 activity in pancreatic carcinomas54
	Metalloproteinases	Identified increased neprilysin activity in aggressive melanoma cell lines31
	Cysteine proteases	Identified increased cathepsin cysteine protease activities in pancreatic islet tumours57. Used for in vivo imaging of tumour cathepsin activity57,60
	Kinases	Inhibitor selectivity profiling of kinase inhibitors35,71
	Caspases	In vivo and ex vivo visualization of apoptosis in colon tumour-bearing mice treated with Apomab62
	Deubiquitylases	Identified increased carboxy-terminal hydrolase UCHL3 and UCH37 activity in HPV cervical carcinomas58
	Cytochrome P450s	Identified the aromatase inhibitor anastrazole as an inducer of CYP1A2 activity68

HPV, human papilloma virus; tPA, tissue plasminogen activator; uPA, urinary plasminogen activator.

^*Blue boxes around structures represent the portion of the activity-based probes that react with the active sites of enzymes.