Elstner et al. found that PPARγ ligands were potentiated by RXRα ligands in multiple breast cancer cells (MCF-7, T-47D, ZR-75-) [42], work that was later confirmed by multiple groups [41, 56] including one study that also found protective effects in Calu-6 lung cancer cells [48]. This evidence concerns the gene PPARG and breast carcinoma.