The expression of IL-15 in CAR cells and their association with NK cells in bone marrow. (A-B) Quantitative RT-PCR analysis of mRNA expression of IL-15 (A) and IL-15Rα (B) in CXCL12-GFP^hi (CAR) cells, CD45⁻CXCL12-GFP⁻ nonhematopoietic cells, CD45⁻CD31⁺ endothelial cells (EC), CD11c^high MHC class II^high DCs, and Gr-1^loMac-1⁺ myeloid lineage cells (Mϕ) in the bone marrow from wild-type mice or CXCL12-GFP knock-in mice. (C) Single-cell RT-PCR analysis of the frequencies of cells expressing IL-15 or IL-15Rα in sorted CAR cells; n = 3. (D) The bone marrow sections from CXCL12-GFP knock-in mice were stained with antibodies against NKp46 (red). Most NKp46⁺ NK cells are in contact with CAR cells (green). *P < .05. **P < .01. ***P < .001.