In our recent studies, we established a mouse line with transgenic expression of a kinase-dead, dominant-negative IGF-1R (MMTV-dnIGF-1R) in combination with MMTV-Wnt1 expression to test how decreased IGF-1R signaling in the mammary epithelium impacts a well-established mouse model of basal-like breast cancer [5]. Here, WNT1 is linked to breast carcinoma.