The expression levels of genes coding for organic anion transporting polypeptides OATPs (SLCOs, n = 12), ABC-efflux pumps related to drug resistance (n = 8), the nuclear receptor PXR and three enzymes with possible relevance to the putative function of the transporters in the turnover of prostaglandins and estrogens (PTGS2, PGDH, and SULT1E1) were studied in samples from serous ovarian cancer together with ESR1 coding for ERα, ESR2 coding for ERβ and HER-2 (Supplementary Tables 1, 2). This evidence concerns the gene ESR2 and ovarian serous adenocarcinoma.