Expression of CCR7 and CCR9 on BM-derived precursors and ETP of wt and single-mutant mice. (A-B) BM cells were stained with antibodies against lineage markers, Sca-1, CD127, CD117, TCRβ, and CCL19-hIg to reveal expression of CCR7 (A) or antibodies against CCR9 (B). LSK and CLPs were defined as lin⁻CD117^hiSca-1⁺ and lin⁻CD127⁺CD117⁺Sca-1⁺, respectively. Data are representative for 5 mice of each genotype from 2 independent experiments. Numbers indicate frequencies of cells within gates. (C) DN thymocytes from wt, CCR7^−/−, and CCR9^−/− mice were stained with antibodies against lineage markers, CD25, CD44, CD117, and CCR9 (left panel) or CCR7 (right panel). Histograms are representative for analysis of 3 individual mice.