Moreover, Lee et al. [55] showed that NaHS inhibited the differentiation of mouse bone marrow cells into multinucleated TRAP-positive osteoclasts in vitro, in addition to reducing the mRNA expression of molecules involved in both nicotine- and LPS-induced osteoclastogenesis (such as RANKL, OPG, M-CSF, MMP-9, TRAP, and cathepsin K), thus suggesting that H2S has a potential therapeutic value for treatment of bone diseases, such as periodontitis. This evidence concerns the gene MMP9 and periodontitis.