CTSB and chronic obstructive pulmonary disease: The cysteine proteases including caspase-1, caspase-3, caspase-7, caspase-8, caspase-9, caspase-11, cathepsin K, and cathepsin S have also been shown to be up-regulated in COPD patients [47,48,49,50,51,52,53,54,55].