Results in these studies demonstrate that when given alone, treatment with γ-tocotrienol, PPARγ agonists (rosiglitazone and troglitazone), or PPARγ antagonists (GW9662 and T0070907), all induce a significant dose-responsive inhibition in the growth of MCF-7 and MDA-MB-231 human breast cancer cells in culture. This evidence concerns the gene PPARG and breast cancer.