CTSK and arthritic joint disease: Similarly, in the “acute” arthritis model, induced by two injections of K/BxN serum8 (Fig. 2e), the paws from Elmo1−/− mice had significantly decreased expression of osteoclast markers Oscar and Ctsk (Fig. 2f), and Elmo1−/− mice exhibited significantly reduced bone erosion (Fig. 2g and Extended Data Fig. 1b).