The human ABCB1 gene, which encodes the multidrug resistance (MDR) transporter P-glycoprotein (P-gp), is expressed in the minority of ovarian cancers at diagnosis, but has been shown to be an adverse prognostic factor in some though not all studies (Baekelandt et al, 2000; Materna et al, 2004; Penson et al, 2004; Hedditch et al, 2014; Sedlakova et al, 2015). The gene discussed is ABCB1; the disease is ovarian carcinoma.