IkB kinase alpha: a link in the chain of the mammary cycle

The transcription factor NF-κB exhibits altered activity in some breast cancers but the relevance of this association has not been established. Cao et al.'s elegant study recently published in Cell reveals a NF-κB-dependent signalling pathway responsible for epithelial proliferation in the mouse mammary gland. Could this mechanism, rather than prevention of apoptosis, be responsible for the reported association between NF-κB and breast cancer? Could the specificity of NF-κB modulators of the IkB kinase complex determine the fate of epithelial cells at different stages of mammary development?