Gene expression in mammary tumors from MMTV-Wnt-1 versus MMTV-Neu transgenic mice. (a) Dendrogram of 35 mammary tumors analyzed by average linkage hierarchical clustering analysis using 1,932 genes selected for high variability across all tumors. 15k arrays were used. The status of Ha-Ras on MMTV-Wnt-1-induced tumors is color coded: red, wild-type; brown, mutant; green, unknown. (b) Western blot analysis for nidogen protein expression on representative mammary tumors from MMTV-Wnt-1 and MMTV-Neu transgenic mice. MMTV, mouse mammary tumor virus; NeuT, mammary tumors from MMTV-Neu transgenic mice; WntT, mammary tumors from MMTV-Wnt-1 transgenic mice.