Altered expression of stem cell regulators in the bystander hematopoietic cells. (A-B) Relative expression of genes in the cells from IR or NR recipients. Homed Lin−Sca-1+ cells were sorted from IR or NR recipients, and mRNA expression of selected genes was examined with real-time RT-PCR. (A) Relative expression of the genes in cells from IR or NR recipients compared with unmanipulated cells. (B) Direct comparison of the gene expression between the cells isolated from IR and NR recipients; n = 3. The primer sequences for those genes are listed in supplemental Table 1. (C) Down-regulation of c-Kit in the IR host. c-Kit expression was measured by flow cytometry 17 hours after BMT. The plots were gated on the donor Lin− population. Bar graphs represents expression of the c-Kit+ fraction in total CD45+ cells homing to BM. **P < .01. n = 2 to 4.