MMP9 and osteoporosis: At the transcriptional level, both tetracycline analogs repressed RANKL-induced mRNA expression of the MMP-9-targeted genes Nfatc1, Lif, and Xpr1. Through using tigecycline and minocycline treatments on zebrafish larvae harboring an osteoporosis phenotype, the antibiotics reduced prednisolone-induced osteoporosis in a dose-dependent manner.