Table 2: Secretion profiles of cathepsins from various cells.

MacrophagesOsteoclastFibroblastCancer cells

Secretion as proformsSecretion as mature active formsNonsecreteSecreted in metastasis cells
Stimulated by PTH
Bone collagen degradation
I cell diseases
Secreted into serum as mature forms
Nonmetastasis cells not secreted