ABCB4 and breast cancer: Also three breast cancer cell lines (MCF-7, ZR-75-1 and MDA-MB-231), three HN cancers (UM-SCC-14C, UM-SCC-22B and RPMI-2650), skin cancer C8161 and HeLa exhibited ABCB4 hypermethylation (>20%; Fig. 2B and C).