Deregulated β-catenin signaling induces the expansion of the basal cell population. A. Whole-mount carmine staining of mammary glands from 10-month-old mice. Bar: 3 mm. B. Separation of luminal (blue ovals, CD24+/CD49low) and basal (red ovals, CD24+/CD49high) epithelial cell populations from 10-month-old mice. C. qPCR analysis of Myc expression in freshly isolated basal (B) and luminal (L) mammary cell populations from 10-month-old virgin mice. D. Percentage of basal cells within the epithelial cell compartment (mean ± SEM of 3 independent experiments; *p < 0.05; **p < 0.001).