Compared to Cul4A, findings linking Cul4B to cancer are less common, however it was still found to be overexpressed in colon cancer (Jiang et al., 2013), cervical cancer, lung cancer, esophageal cancer, and breast cancer (Hu et al., 2012), with its overexpression closely related to tumor stage, invasion and metastasis. This evidence concerns the gene CUL4A and breast cancer.