(A) In circulating tumor cells isolated from SCID/Beige mice engrafted with TU-BcX-2O0, there is high percentage of CD44+ and a low percentage of CD24+ cells, indicative of a stem cell-like population. Furthermore, circulating cells also expressed CD326, or EpCAM, another stem cell-associated protein. Data was collected by flow cytometry, and protein expression is represented by percentage of total circulating cells. Data was collected in duplicate. (B) Flow cytometry dot plots of circulating tumor cells isolated from blood specimen of TU-BcX-2O0T5. Populations in blue are CD44low and populations in gold are CD44low. (C,D) Treatment of TU-BcX- 2O0 with LBH589 (100nM, 10 days) results in significantly reduced sizes of mammospheres. Error bars represent SEM and significantly different = *p < 0.05, *** p < 0.001.