Negatively charged amino acids at the COOH-terminus of the integrin α1 tail inhibit cell adhesion and migration, but not proliferation. (A) Schematic representation of mutants generated from the full-length integrin α1 subunit. (B) CHO cells were transfected with either empty vector or the integrin α1 mutant cDNAs indicated in panel A, and cell populations were sorted by FACS using anti–human integrin α1 antibodies. (C) The CHO cell populations indicated were plated on 10 μg/mL collagen IV and after 1 hour they were fixed and stained with rhodamine-phalloidin. A representative cell is shown for each cell population. Bar represents 10 μm. (D-F) Cell adhesion (D), migration (E), and proliferation (F) were determined as described in Figures 1 and 2. * indicates statistically significant differences (P < .05) between the vector transfected and α1 mutant–expressing CHO cells.