WIF1 and invasive breast carcinoma: For example, a reduced expression of Wnt-inhibitory factor (WIF1) was seen in 60% of invasive breast carcinomas (Wissmann et al., 2003), and SFRP1 expression, a secreted Wnt antagonist present in breast epithelium, was shown to be lost in 80% of invasive breast carcinomas (Ugolini et al., 2001).