Fig. 6

Py230 MaCSC model. Py230 MaCSCs undergo lineage differentiation in vitro in response to appropriate stimuli. We postulate that the alveolar-like cells develop from luminal cells and that adipocyte-like cells differentiate from the multipotent MaCSC, hence the dashed lines. In vivo, Py230 MaCSCs consistently form luminal tumors. With serial passaging in vivo, epigenetic and/or genetic changes taking place during tumor progression that can lead to clonal evolution and tumor heterogeneity. We have derived clonal cell lines that give only to claudin-low tumors or basal-like tumors. To date we have not isolated clonal cell lines that give rise to Her2 tumors