CDKN2A and breast carcinoma: Overexpression of B lymphoma Moloney murine leukemia virus insertion region-1 (BMI1), a transcription repressor that operates in stem cell maintenance and oncogenesis through inhibition of INK4A/ARF tumor suppressor locus, has been linked with increased incidence of metastasis in human gastric and breast cancer, as well as melanoma and other cancer types.