Two of our previous studies showed that when EGCG was given in association with a synthetic retinoid X receptor-γ (RXRγ) agonist named 6-OH-11-O-hydroxyphenanthrene (IIF) to breast carcinoma [17], cholangiocarcinoma and colorectal carcinoma cell lines, cytotoxicity increased [18]. This evidence concerns the gene RXRG and breast carcinoma.