When IGFBP5 knockdown via shRNA is combined with Wnt1 inhibition using the frizzled8 fusion protein, the effect of the fusion protein is diminished and tumor volumes increase over time, indicating that the mechanism by which Wnt1 promotes tumor growth is dependent on downregulation of IGFBP5 in a breast cancer model (103). This evidence concerns the gene WNT1 and breast carcinoma.