When comparing each of the OC histotypes to the samples with mixed histotypes by Mann–Whitney Test, we observed a significantly higher CUL4A expression in serous adenocarcinoma (p = 0.01) and a lower DDB1 expression in mucinous adenocarcinoma (p = 0.004), whereas no significant differences in CUL4A or DDB1 expression was observed in other histotypes (Supplementary Fig. 1g, h). Here, CUL4A is linked to serous adenocarcinoma.