K1146A point mutation of the integrin α1 cytoplasmic tail leads to decreased endothelial cell adhesion and migration. (A) Schematic representation of single point mutants (K/A) generated from the full-length integrin α1 subunit. (B) α1KO endothelial cells were transduced with either empty vector or the integrin α1 mutant cDNAs indicated in panel A, and cell populations were sorted by FACS using antihuman integrin α1 antibodies. (C) Total cell lysates of the cell populations were used to detect the levels of full-length and mutant human integrin α1 as well as mouse β1 subunits as described in detail in Figure 1C. (D-G) Cell adhesion on different concentrations of collagen IV (D) or in the presence of anti–human integrin α1 antibodies (E) as well as migration in the absence (F) and presence (G) of anti–human integrin α1 antibodies were determined as described in Figure 1. Note that only cells expressing K1146A mutant fail to adhere and migrate on collagen IV. * indicates statistically significant differences (P < .05) between the α1KO and the α1 mutant–expressing endothelial cells; * indicates statistically significant differences (P < .05) between untreated and antibody-treated α1 mutant–expressing cells. (H,I) The endothelial cells indicated were plated on 10 μg/mL collagen IV or fibronectin. After 4 hours, the cells were fixed and stained with rhodamine-phalloidin. A representative cell is shown for each cell population. Bar represents 10 μm.