TN-C is predominantly expressed in stromal and endothelial cells and its ligand, integrin α9, is expressed on HSPCs. (A-B) Relative RT-PCR for TN-C mRNA expression on whole-BM (A) and on CD45⁺, CD11b⁺, CD31⁺CD45⁻, PDGFRα⁺CD45⁻, and LSK cells (B; n = 5). (C-E) IHC of BM obtained from Cxcl12^+/EGFP mice on day 10. Note that TN-C proteins (red) are deposited around CD31⁺ (blue) endothelial cells (arrows) or CAR cells (green; arrowheads). (F) Relative expression of TN-C mRNA in isolated CD45⁻Ter119⁻CD31⁺Sca1⁺ (ECs), Cxcl12^neg and Cxcl12^high cells on day 10 (n = 5). (G-N) Relative expressions of integrin α9 (G), integrin β1 (H), integrin α4 (I), integrin αV (J), integrin α5 (K), integrin α7 (L), integrin β3 (M), and integrin β6 (N) in whole BM cells (n = 6). (O) Flow cytometric analysis of integrin α9 and integrin β1 expression by LSK cells. (P) Ratio (Lin⁺ = 1) of mean fluorescence for integrin α9 and integrin β1 in the Lin⁺ and LSK fractions (n = 7). *P < .05. Scale bar indicates 50 μm.