However, TPS-A has also been shown to inhibit tubulin polymerization and breast cancer resistance protein (BCRP, ABCG2) [11], and an effective inhibition of BCRP by TPS-A has been shown to restore the efficacy of clinically used chemotherapeutics when tested on BCRP+ breast cancer cell lines [12]. Here, ABCG2 is linked to breast cancer.