The NF-kB has been shown to regulate positively osteoclast differentiation, and negatively modulate osteoblast differentiation.104,105 Although mice lacking NF-kB exhibited osteopetrosis due to an increase in bone resorption and bone formation in vivo, the phenotypic changes of osteoclasts lacking NF-kB in vitro were inconsistent with the osteoclast cultures derived from Lrrk1 KO mice, ruling out involvement of NF-kB signaling in LRRK1 regulation of osteoclast function.106. This evidence concerns the gene LRRK1 and osteopetrosis.