Recent studies suggest that there is an extensive cross-talk between integrin, c-Src, and Rho signaling pathways.90 The osteopetrosis phenotype in Lrrk1 KO mice are much more severe than the c-Src KO, integrin beta 3 KO, or RAC1/2 double KO mice, although these mice display partially overlapping skeletal abnormalities that are caused by defective bone remodeling and dysfunctional osteoclasts. This evidence concerns the gene RAC1 and osteopetrosis.