We have reported previously the upregulation of TNFα-induced adipose-related protein (TIARP) [also known as six-transmembrane protein of prostate 2 (STAMP2) and tumor necrosis factor α-induced protein 9 (TNFAIP9)] in glucose-6-phosphate isomerase (GPI)-induced arthritis, especially in CD11b+ splenocytes and synovia of mice5. Here, STEAP4 is linked to arthritic joint disease.