Generation of integrin α1-null endothelial cells expressing deletion mutants lacking Glu¹¹⁵⁰ and/or Lys¹¹⁵¹ of the integrin α1 cytoplasmic tail. (A) Schematic representation of the cytoplasmic truncation mutants of the human integrin α1 cDNA. (B) α1KO endothelial cells were transduced with either empty vector or the integrin α1 mutant cDNAs indicated in panel A, and cell populations expressing the integrin α1 constructs were sorted by FACS using anti–human integrin α1 antibodies. (C) Total cell lysates of the cell populations were used to detect the levels of full-length and mutated human integrin α1 as well as mouse β1 subunits as described in detail in Figure 1C. (D,E) Integrin α1KO endothelial cells expressing vector alone or the truncation mutants 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.