Cao et al. BMC Cancer 2010, 10:68 http://www.biomedcentral.com/1471-2407/10/68 Page 6 of 11 Figure 2 Validation of SP cell fraction increase by cultured with macrophage-like cells in human neuroblastoma cell line SK-N-CH. (A) Conditioned culture SK-N-CH cells show higher percentage of the CD133-PE population by FACS. (B) Immunofluorescence staining confirms the higher expression of CD133 (green). The images shown are representative of cells after cultivation for 24 hours. Nuclei were counterstained with DAPI (blue). Original magnification ×600.