FOXO3 and breast cancer: In agreement with the previously established role of FoxO3a in tumour growth [21, 42–46], osteoclast function and osteoblast differentiation [47], we have found that inhibition of IKKβ interaction with FoxO3a in osteotropic MDA-231 breast cancer cells overexpressing IKKβ inhibited their growth and diminished their ability to stimulate osteoclasts and to suppress osteoblast differentiation.