Four-color analysis of DN thymocytes by flow cytometry. Isolated DN thymocytes were 4-color stained for CD117-APC, and CD44-cychrome, CD25-FITC, and additional markers revealed by streptavidin-PE. CD44⁺ cells were separated into CD117 highly positive cells and CD117^– cells and these populations defined as populations A and B. (A) Representative flow cytometric profile of cells from population A that were further analyzed according their expression of CD25 and lineage-specific as well as hematopoietic development common surface markers. (B) Representative flow cytometric profile of cells from population B.