Flow cytometric analysis of EYFP expression in adult bone marrow cells. End-SCL-Cre-ER^T;R26R-EYFP BM was harvested 6 weeks after 2 weeks of daily 2 mg tamoxifen (TAM) injections. (A) EYFP analysis within total adult BM. No Cre-mediated recombination was detected within BM of either untreated or in the majority of tamoxifen-treated mice. (B) EYFP expression within the c-kit⁺Sca-1⁺lineage^- population. In 1 of 4 tamoxifen-treated mice, recombination was detected in total BM (A, right) as well as in the c-kit⁺Sca-1⁺lineage^- population (B, right). (C) Additionally, we determined the activity of the end-SCL-Cre-ER^T transgene in BM ECs (CD31⁺CD45^-Ter119^- population). In 2 of 3 mice, we could not detect any EYFP expression in BM endothelium. To demonstrate sufficient activity of the Rosa locus in the BM populations investigated, we analyzed CMV-Cre; R26R-EYFP BM as a positive control for EYFP expression. (B-C) Representative histograms (gray, end-SCL-Cre-ER^T; R26R-EYFP; dotted, CMV-Cre; R26R-EYFP) are shown. Percentages indicate proportions of EYFP-positive cells of end-SCL-Cre-ER^T; R26R-EYFP mice. FSC indicates forward light scatter.