<unk> s are a family of calcium-dependent cysteine proteases, which play essential roles in apoptosis (programmed cell death), necrosis and inflammation.<unk> s are essential in cells for apoptosis, one of the main types of programmed cell death in development and most other stages of adult life, and have been termed "executioner" proteins for their roles in the cell. Some<unk> s are also required in the immune system for the maturation of cytokines. Failure of apoptosis is one of the main contributions to tumour development and autoimmune diseases; this coupled with the unwanted apoptosis that occurs with ischaemia or Alzheimer's disease, has boomed the interest in<unk> s as potential therapeutic targets since they were discovered in the mid 1990s.
They are called cysteine proteases, because they use a cysteine residue to cut those proteins, and are called<unk> s because the cysteine residue cleaves their substrate proteins at specific asparagine residues.
Caspase
ATPase
Isozyme
Phosphatase
Enzyme
Receptor 
Diastase
Metalloproteinases 