Cathepsins K, L, and S activity detection in human breast tissue. A) 10 μg of normal and tumor breast tissue from patient biopsies were loaded for zymography. Cathepsin K band is visible at 37 kD, cathepsin L at 21 kD, and cathepsin S at 25 kD. Representative zymogram is shown and cropped for clarity. B) Cathepsin activities were quantified with densitometry of each band on the gel. C) The same samples were loaded for MMP zymography. A representative MMP zymogram is shown and cropped for clarity. D) Pro- and mature MMP-9 and MMP-2 activities were quantified by band densitometry. All values are fold change of tumor compared to normal (n = 10, #p < .005, *p < .002, ** p < .05).