Chemotactic migration of TIMP-1^−/− HSCs toward CXCL12 and expression of CD44 and p53. (A-B) Percentage of chemotactic migration, toward a gradient of CXCL12, of Sca-1⁺ cells or CD150⁺48⁻KSL HSCs from WT or TIMP-1^−/− mice. Chemotactic assays were performed with transwell chambers, and cells were allowed to migrate for 4 hours at 37°C, 5% CO₂. (C) MFI of CXCR4 expression on BM CD150⁺ 48⁻KSL HSCs. (D-E) MFI of CD44 expression on the cell membrane of WT and TIMP-1^−/− SP^KLS HSCs. Results are reported as mean ± SEM of at least triplicate experiments; *P < .05. (F) p53 expression was measured in WT and TIMP-1^−/− SP^KLS cells by real-time PCR. Values are the average of duplicate experimental replicates. For each group, SP^KLS cells from 3 different animals were pooled together for RNA extraction; *P < .05.