For analysis of CD133 expression cells were stained with allophycocyanin (APC) conjugated monoclonal CD133/1 (AC133) antibodies (Miltenyi, Bergisch-Gladbach, Germany), according to the manufacturer's general protocol for immunofluorescent staining (for 10 min in the dark at 4uC). CD133-APC was excited at 635 nm, the fluorescence was measured through 670/ 30 BP optical filter, and alive CD133+ cells were defined on SSC versus FL6 (in logarithmic mode) dot plot. Non-stained cell suspension was used as a control. GFP+ tumor cells were sorted in ''purify 1'' mode into polypropylene round-bottom Falcon tubes (Becton Dickinson Labware Europe, France) containing culture media, that were placed on ice. Aliquots from some samples at the end of the sorting were removed and reanalyzed for control of the sort purity that was greater than 98%.