Casflox/flox and Relaflox/+ mice of C57BL/6 background (35, 36) were mated with Dmp1-Cre transgenic mice, in which the Cre recombinase gene was specifically expressed in osteocytes (37). Dmp1-Cre+/−, Casflox/flox (Cas cKO) and Dmp1-Cre−/− Casflox/flox (normal littermates) mice were generated by mating Dmp1-Cre−/−, Casflox/flox male mice with Dmp1-Cre+/−, Casflox/+ female mice. Dmp1-Cre+/−;Casflox/flox;Relaflox/+(Cas/Rela cKO) and Dmp1-Cre−/−;Casflox/flox;Relaflox/+ (normal littermates) mice were generated by mating Dmp1-Cre+/−;Casflox/flox;Rela +/+ male mice with Dmp1-Cre−/−;Casflox/flox;Relaflox/+ female mice. Dmp1-Cre+/–Relaflox/+ (Rela cKO) and Dmp1-Cre−/−;Relaflox/+ (normal littermates) mice were generated by mating Dmp1-Cre+/−;Rela +/+ male mice with Dmp1-Cre−/−;Relaflox/flox female mice. All animals were housed under specific pathogen–free conditions and treated with humane care under approval from the Animal Care and Use Committee of Tokyo Metropolitan Institute of Gerontology, National Rehabilitation Center for Persons with Disabilities, and Nadogaya Hospital. For all mouse analyses except for those at 1 day after birth (fig. S1), male mice were used.