SP7 and osteopetrosis: A recent study reported that the inactivation of Rankl specifically in osteoblast lineage cells from mice with the use of an Osterix-Cre transgene, results in typical osteopetrosis in the tibia, which indicated a potential role for this pathway.47 Taken together, in our study, we believe that the OsxCre;R26dn/dn mice exhibit osteopetrosis-like disorder in a previously unreported osteoblast-originated “osteoclast non-autonomous form”, which mimics osteopetrosis functionally rather than genetically.