Cytotoxicity observed in a long-term exposure of carcinoma-derived cell lines to an ENN mixture containing 19% ENN B was significantly reduced when breast cancer resistance protein (ABCG2) or P-glycoprotein (P-gp) were present, indicating that ENNs are substrates for these transport proteins (Dornetshuber et al. 2009b). Here, PGP is linked to carcinoma.