Figure 4

Effect of Notch signaling on branching morphogenesis. (a) Fragment of the human mammary gland, after 8 hours of collagenase digestion of the reduction mammoplasty sample. (b) Complex ductal–alveolar structure developed in 18 days, from a mammosphere embedded in Matrigel. (c) Secondary mammospheres were embedded in Matrigel and treated with DSL peptide or Notch4 blocking antibody (N4Ab). Longer branches developed earlier in the presence of DSL peptide. (d) In addition, more spheres developed branching structures. The Notch4 blocking antibody completely inhibited proliferation and branching in Matrigel (c, d). Images shown in (c) are representative of 100–150 structures per experiment, scored in three different experiments with cells derived from three different patients. Data are presented as the mean ± standard error of the mean.