Figure 2: Frequency of CD133+ cells in primary tumors is maintained in PDXs during passaging in mice independently of their initial content. Dot plots showing that the percentage of CD133+ cells, previously demonstrated to display stem-like features and to be spared by cisplatin treatment [REF], is similar in the primary tumor and in PDXs. CD133+ cells levels remain stable also after several passages in immunocompromised mice in PDX models established from low, intermediate and high CD133-expressing tumors (LT48, LT128, LT111 resp.). p = number of serial transplant in mouse. FACs analysis of CD133 expression was performed with CD133/1-phycoerythrin antibody (50 μg/mL; AC133 clone; Miltenyi Biotech).