C/N ratios for cathepsin H enzyme activity correlated significantly with C/N ratios for the 29 kDa mature single-chain protein form (P< 0.001), with increased activity most commonly associated with elevated expression of 29-kDa cathepsin H but also with up-regulation of the 22-kDa band, suggesting a shift to more fully processed, mature active cathepsin H protein forms in cancers. This evidence concerns the gene CTSH and cancer.