DEK and breast cancer: As a well-established oncogene, DEK overexpression has been documented in a continually expanding list of malignant neoplasms, including hepatocellular carcinoma, brain cancer, bladder cancer, retinoblastoma, T cell large granular lymphocytic leukemia, breast cancer, cervical cancer, melanoma, chronic lymphocytic leukemia, colon cancer, head and neck squamous cell carcinomas, and prostate cancer [42, 54–65]. DEK overexpression is most frequently caused by aberrant transcription via E2F [66], YY1, NF-Y [67], and ER-α transcription factors [68].