The dramatic rise in COX-2 protein levels following depletion of HECTD4 under anchorage-independent culture is also seen in MDA-MB-468 cells (SI Appendix, Fig. S4G) as well as two other breast cancer cell lines BT-549 and HCC1143 (SI Appendix, Fig. S4 H and I). Here, HECTD4 is linked to breast cancer.