ABCB1 and ovarian serous adenocarcinoma: Also, a recent study showed that in nearly 8% of high-grade serous ovarian cancers with acquired resistance to paclitaxel, translocations and inversions of the 5′ regulatory region of the ABCB1 gene lead to MDR1 overexpression compared to patient-matched, paclitaxel-sensitive primary tumors [46].