Since our previous study has shown that cryptotanshinone could inhibit MCF-7 and SKBR-3 cells through GPER pathway and c-Fos as well as c-Jun are downstream of GPER, we intend to investigate whether GPER is also involved in the efficacy of Tan IIA on another breast cancer cell line MDA-MB-231. This evidence concerns the gene FOS and breast carcinoma.