(A) Primary Wt or Limd1−/− calvarial osteoblasts were cultured in normal or osteogenic media for 12 days then fixed and stained with Alizarin Red S to detect mineralization. The number of Alizarin positive nodules were counted and graphed. Data is a compilation of three different experiments, all performed in triplicate. For rescue experiments, Limd1−/− calvarial osteoblasts were infected with either myc-empty or myc-Limd1 retroviruses before exposure to osteogenic culture conditions. Aliquots of Limd1−/− cells infected with myc-empty or myc-Limd1 were lysed and equal amounts of protein run on SDS-PAGE then Western blotted for the presence of Limd1. (B) Immortalized Wt or Limd1−/− calvarial osteoblast were cultured in osteogenic conditions for 12 days then fixed, stained with Alizarin Red S, and the percentage of Alizarin Red S staining determined and graphed. (C) Equal numbers of primary Wt or Limd1−/− calvarial osteoblasts and wt BMDM were co-cultured in the presence of vitamin D for 10 days then fixed and TRAP stained to identify osteoclasts (white arrows). The number of TRAP positive osteoclasts was quantified and graphed. For rescue experiments, Limd1−/− calvarial osteoblasts were infected with either myc-empty or myc-Limd1 retroviruses before co-culturing. *Indicates a significant difference between Limd1−/− and Wt (*p<0.05, **p<0.01, ****p<0.001, student’s paired t-test).