Fig. 2

CD133+ cells were more radioresistant then CD133- cells. a Flow Cytometric analysis of the isolated CD133+ cells. The CD133+ cells were isolated from A549 and H157 cells by immunomagnetic sorting using CD133+ antibody-conjugated magnetic microbeads. The isolated CD133+ cells were stained by anti-CD133+ antibody and subjected into flow cytometric analysis. The dotted and solid lines show fluorescent distributions of unseparated and separated cell populations. Greater than 90 % purity was found in isolated CD133+ cells. b Higher expression of CSC markers in isolated CD133+ than unseparated A549 cells. mRNA expression of the indicated CSC markers in isolated CD133+ cells were analyzed by qPCR analyses. c Sphere formation Assay using isolated CD133+ cells of A549 and H157 cell line. d Clonogenic survival curves of CD133+ and CD133- cells. CD133+ cells and CD133- cells of A549 and H157 cells were seeded, irradiated at different doses, and survived clone numbers at 7–9 days of incubation were counted. The surviving fraction was obtained from normalized plating efficacies (70-75 % for CD133- cells and 30-35 % for CD133+ cells). *p < 0.05, **p < 0.01, ***p < 0.001