CTSK and osteoporosis: Ma et al. [138] investigated the therapeutic effects of tectorigenin on osteoporosis, and the results showed that tectorigenin reduced mRNA levels of osteoclast-specific genes, including nuclear factor of activated T cell cytoplasmic 1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase (MMP)-9 and cathepsin K in RAW264.7 cells, and bone marrow mononuclear cells, and mitigated the bone loss in osteoporosis mice [138].