Furthermore, a similar effect was observed in both in vitro (epidermal carcinoma-derived cell line KB-3-1, the promyelocytic leukaemia cell line HL60, the non-small cell lung cancer cell lines A549, VL-6 and VL-8, the small cell lung cancer cell line GLC-4, the glioblastoma U373, the hepatocellular carcinoma cell line Hep3B, and the breast cancer cell lines MCF7 and MDA-MB-231) and in vivo (human colon carcinoma xenograft) models overexpressing ABCB1, ABCC1 or ABCG2 proteins for lanthanum compound KP722. This evidence concerns the gene ABCG2 and breast carcinoma.