Figure. 1.

Both human prostate and breast are susceptible to tumorigenesis. The prostatic and mammary glands are two-layered secretory structures and recent lineage tracing studies in both organs suggest that luminal cells are preferred targets of tumorigenic transformation (middle, boxed area). The pile of cells below the arrow indicate disorganized cells in early hyperplastic lesions and different shapes, colors, and sizes signify tumor cell heterogeneity. We acknowledge Dr K Rycaj and Ms J Holcombe and Ms C Brown at the University of Texas MD Anderson Cancer Center in helping to make this figure.