KRT18 and neoplasm: Marker expression analysisof the dominant tumor subtypes revealed mixed expression of smooth muscle actin (SMA) andcytokeratin 5 (K5), K6, K14 (basal markers), K18 (luminal marker), vimentin, ERα, as well asnuclear co-localization of β-catenin and cyclin D2 (Supplementary Fig S1), a pattern oftenfound in other tumor models of mixed lineages such as MMTV-WNT1 (Li et al,2003).