Research is being conducted on the role of cathepsin K in regulating tumor growth and metastasis, particularly in castration-resistant prostate cancer. The enzyme's involvement in various cancer types, including breast cancer and glioma, is also being explored, with studies examining its relationship to immune cells, metastasis, and potential therapeutic targets. The specific mechanisms and pathways, such as the IL-17/CTSK/EMT axis and M2 macrophage polarization, are being investigated to better understand the enzyme's function in cancer progression.