Treatment with 0.5–6 μM  γ-tocotrienol, 0.4–50 μM PPARγ agonists (rosiglitazone or troglitazone), or 0.4–25 μM PPARγ antagonists (GW9662 or T0070907) alone resulted in a dose-responsive inhibition of MCF-7 and MDA-MB-231 breast cancer proliferation. The gene discussed is PPARG; the disease is breast cancer.