Fig 7.

Rapid mobilization of TG2 to the cell surface by sFXIIIA and antibody crosslinking of α1 integrin subunit. To determine if FXIIIA-induced movement of TG2 to the cell surface is integrin dependent, aliquots of 5 × 10³ human articular chondrocytes were starved in serum-free DMEM high glucose medium for 2 hours and then stimulated with sFXIIIA, the α1 integrin subunit antibody, TS2/7 (with and without crosslinking by anti-mouse IgG) versus an IgG control antibody. Additionally, after starvation the chondrocytes were pretreated with the blocking α1 integrin subunit antibody, FB12 and then stimulated for 5 and 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 strepavidin-AP antibodies as described in the Methods.