CD98 engagement increases the surface expression of β1 integrin. (A) Freshly cultured MCF-7 cells were dispersed and then incubated with anti-CD98 mAb UM7F8 and secondary Ab (blue line) for 1 h. As negative controls, cells were treated with mouse IgG and secondary Ab (red line). FITC-conjugated anti-CD29 mAb was used to measure the expression level of β1 integrin on the cells treated with mAbs as described above. An FITC-conjugated mouse anti-human lgG was used as the negative control (green line). (B) Cell extracts from MCF-7 cells treated as in (A) were analyzed by Western blotting using anti-β1 integrin and anti-actin mAb.