ABCB1 and cancer: Four human cancer cell lines, DLD-1 (colon cancer), SNB-75 (glioblastoma), Hs 578 T (breast cancer), and MDA MB 231 (breast cancer) were treated with an RSK inhibitor (SL0101), ABCB1 inhibitor (zosuquidar), or HIF-1α inhibitor (Fig. 7).