Since the discovery that Bcl-3 is an oncogene involved in leukemia, other studies have demonstrated the oncogenic function of Bcl-3 in solid tumors originating from breast [15–17], liver [18], prostate [19], colon [20–23], cylindromatosis [24], basal cell carcinoma [25], squamous cell carcinoma [26], and nasopharyngeal carcinoma [27]. This evidence concerns the gene BCL3 and leukemia.