This is somewhat unexpected as FOXO3a is a well-established tumour suppressor;2, 9 however, it has also been shown to have a role in cell renewal and expansion.23, 24 Despite the fact that both FOXK2 overexpression and FOXO3a depletion independently repressed cell proliferation, MCF-7 cells with simultaneous FOXK2 overexpression and FOXO3a depletion displayed similar proliferative rates as the cells with FOXO3a silenced only, suggesting that FOXO3a is essential for the anti-proliferative function of FOXK2. This evidence concerns the gene FOXK2 and neoplasm.