NFKB1 and breast carcinoma: We had previously demonstrated feasibility of generating MDA-MB-231 breast cancer cells overexpressing IκBαSR.28 MDA-MB-231 cells have constitutively active NF-κB, and IκBαSR reduced basal and tumor necrosis factor alpha (TNFα)-inducible activation of NF-κB (Figure 2a).