Fig. 7. Rapid mobilization of TG2 to the cell surface by either sFXIIIA or antibody crosslinking of 1-integrin subunit. To determine whether FXIIIA-induced movement of TG2 to the cell surface is 1-integrin-subunit dependent, aliquots of 5x10³ human articular chondrocytes were starved in serum-free high-glucose DMEM for 2 hours and then stimulated with sFXIIIA, the 1-integrin-subunit antibody TS2/7 (with and without crosslinking by anti-mouse IgG) versus an IgG control antibody. Additionally, after starvation the chondrocytes were pre-treated with the blocking 1-integrin-subunit antibody, FB12 and then stimulated for 5 or 10 minutes with WT sFXIIIA. After fixation of the cells, TG2-specific antibodies were used to detect membrane-bound TG2, quantified through successive incubations with biotin anti-rabbit and streptavidin-AP antibodies as described in Materials and Methods.