BMP4 inhibits BT-474 cell growth in 3D cell culture. (A) Cells were grown in Matrigel and supplemented with 100 ng/ml BMP4 or vehicle. Images were taken as indicated in Figure 2 and representative examples from day 14 are shown. Scale bars 200 μm. (B) Cell proliferation and (C) area covered by cell clusters were measured and are presented as in Figure 2, *P < 0.05.