HBEGF and Arthritis: Further supporting a role of osteoclasts as contributors to osteoproliferation in the K/BxN serum transfer arthritis model, we used a mouse model, in which a genetic construct encoding the diphtheria toxin receptor is fused to the CD11c promoter region (CD11c-DTR),25 which we recently showed to target osteoclasts and their precursors.26