A landmark paper by Cheng et al. [12] showed that these HOX genes were not expressed in normal adult OSE but were responsible for inducing lineage specificity in ovarian cancers, with HOXA9 promoting a papillary serous phenotype, HOXA10 endometrioid and HOXA11 mucinous ovarian adenocarcinoma (see Figure 1). This evidence concerns the gene HOXA9 and ovarian cancer.