Flow cytometric analysis of integrins. Analysis was performed for integrin α5 (A) and α6 (B) on mouse breast cancer cell lines 4T1 (control), as well as 4T07 and 67NR. The fluorescence signals of unstained cells (primary antibody omitted) for each cell type were presented as blue peaks and served as the basal level of cell-surface expression. The fluorescence signal for integrin α5 and α6 subunits were presented as open peaks. Histograms presented the positive cell percentage of each cell type and the differences are statistically significant (P < 0.01). All experiments were repeated three times.