Colony formation of CD133+ cord blood cells in the presence of C21 and OPN. (A) Microscope images of 4 typical colonies formed after 18 days in culture of CD133+ cells in the semisolid serum-free medium described in Methods. The "Methocult"-medium contained stem cell factor, GM-CSF, G-CSF, IL-3, IL-6 and EPO. The culture was not done on stromal cell monolayers and did not contain Flt3 ligand, thrombopoietin or VEGF. (B) Total colony cell count observed after 18 days incubation with C21, OPN or C21+OPN. Mean ± SEM. n = 4. P value according to Friedman Test (nonparametric repeated measures analysis of variance) and Dunn's multiple comparisons test.