To identify the roles of CUL4-DDB1 E3 ligase complex in ovarian cancer cells, we performed a knockdown of CUL4-DDB1 E3 ligase components, ring of cullin-1 (ROC1), DDB1, or DDB1/CUL4-associated factor-1 (DCAF1) in A2780 cells, and detected 5hmC levels by dot-blot assays (Figure 2E and 2F). This evidence concerns the gene DDB1 and ovarian cancer.