Effects of Ad5E1mIL-4 on osteoclast-like cells. (a–d) Arthritic knee joint of a mouse 7 days after intra-articular injection of 1.107 pfu of Ad5del70-3 control vector. Note the TRAP-positive mononuclear cells in the erosive front (red). (e–h) Knee joint of a mouse 7 days after intra-articular injection of 1.107 pfu of Ad5E1mIL-4. Note the decreased number of TRAP-positive mononuclear cells. e, ×100. a–d and f–h, ×200. P, patella; F, femur; JS, joint space; C, cartilage; S, synovium; CB, cortical bone; TP, tibia plateau.