Figure 6

Estrogen-responsiveness in MCF-7 wild-type and LM-specific α₆ integrin transfectants. Wild-type MCF-7 cells were plated (50,000 cells per well) on 24-well plates on either Col I or LM (a) and α₆a and α₆ transfectants were plated on Col I (b) in serum-free medium (SFM). The cells were treated with ICI 182,780 (200 nM) for 24 hours, followed by indicated treatments (17β-estradiol [E₂] 20 nM, IGF-1 25 ng/ml) for 24 hours, labeled with ³H-thymidine for 3 hours and assayed for ³H-thymidine incorporation into DNA. Col I, collagen type 1; E₂, 17β-estradiol; ICI, ICI 182,780; IGF-1, insulin-like growth factor I; LM, laminin.