To examine the effect of dominant negative PEA3 on Wnt1-driven tumorigenesis, we compared tumor latency in MMTV/Wnt1 and bigenic MMTV/Wnt1, MMTV/ΔNPEA3En virgin females, generated by interbreeding MMTV/Wnt1 mice with MMTV/ΔNPEA3En animals. Here, WNT1 is linked to neoplasm.