Figure 5.

High susceptibility of CD133^hi SNU-475 cells to TRAIL-induced apoptosis and caspase activation. (A) After treatment of CD133^lo and CD133^hi SNU-475 cells with the indicated concentrations of TRAIL for 6 h, percentage of apoptotic cells in both cells was determined with flow cytometry using annexin V and PI double staining. The bottom right quadrant of each dot plot represents early apoptotic cells (annexin V positive/PI negative). The upper right quadrant represents late apoptotic cells (annexin V positive/PI positive). (B) For both cells treated with TRAIL (5 or 25 ng/ml for 6 h), the activation of caspases and cleavage of PARP (cl. PARP) were determined by Western blot analysis.