Figure 4

Synovial osteoclasts in human tumour necrosis factor transgenic (hTNFtg) and JNK1^-/-hTNFtg mice. As demonstrated by staining with tartrate-resistant acid phosphatase (a), there are abundant osteoclasts (OC) at the site of erosions in hTNFtg and intercrossed (JNK1^-/-hTNFtg) mice, which all developed arthritis (magnification 100×). The number of osteoclasts was similar in the two animal groups (b). Vertical bars indicate standard deviation. JNK, c-Jun N-terminal kinase.