The year 1999 brought us 233 new publications to read, many of which concerned the effects of PPARγ agonists on the growth and differentiation of human cancer cells in cancer tissues (ureter, bladder, prostate, liposarcoma) or cell lines such as colon cancer cells, T-cell lymphoma, or breast cancer cell lines [67,68,69,70,71]. This evidence concerns the gene PPARG and breast cancer.