In our present study, low expression of NF-κB p65 as well as IκBα in cytosol and high expression of NF-κB p65 in nucleus of mammary tumor cells from DMBA control animals suggest possible degradation of IκBα, subsequent release of activated NF-κB p65 and its eventual translocation to the nucleus. The gene discussed is NFKB1; the disease is breast cancer.