Activation of PPARγ negatively regulates cell cycle progression by modulating a number of cell cycleregulators: (1) inhibiting E2F activity in transformed adipogenic cells [24], (2) Rb hyperphosphorylation in vascular smooth musclecells and pituitary adenoma cells [25, 26], (3) cyclin D1 expression in Ras-transformedintestinal epithelial cells, pancreatic, or breast cancer cells [27–29], and (4) inducing CDK inhibitor expressionsuch as p18, p21, and p27 in hepatoma cells [30]. The gene discussed is PPARG; the disease is breast cancer.