WNT-Mediated Regulation of FOXO1 Constitutes a Critical Axis Maintaining Pubertal Mammary Stem Cell Homeostasis.

Puberty is characterized by dynamic tissue remodeling in the mammary gland involving ductal elongation, resolution into the mature epithelial bilayer, and lumen formation. To decipher the cellular mechanisms underlying these processes, we studied the fate of putative stem cells, termed cap cells, present in terminal end buds of pubertal mice. Employing a p63-based lineage-tracing strategy, we identified a unipotent fate for proliferative cap cells that only generated cells with basal features.