FIGURE 4.

Effect of the DE loop point mutations on α₄β₇-mediated cell adhesion on MAdCAM-1 substrates in shear flow. A and B, rolling and firm adhesion on MAdCAM-1 substrates of α₄β₇ 293T transfectants in 1 mm Ca²⁺ + 1 mm Mg²⁺ (A) and 0.5 mm Mn²⁺ (B). The number of rolling and firmly adherent α₄β₇ 293T transfectants was measured in the indicated divalent cations at a wall shear stress of 1 dyne/cm². The experiment was performed on the surface coated with WT or mutant MAdCAM-1 (10 μg/ml). The cells preincubated with the α₄β₇ blocking mAb Act-1 (2 μg/ml) at 37 °C for 5 min or treated with 5 mm EDTA were used as control. Error bars are ±S.D. (n = 3). *, p < 0.05, **, p < 0.01, when compared with MAdCAM-1 WT.