EPC mobilization is enhanced in SK-deficient mice and protects against ischemic injury. (A) WT and SK-1-KO mice, no treatment (−) or administered with PBS or EPO (1000 IU/kg) for 3 consecutive days. Circulating blood was collected and Lin⁻/c-kit⁺ cells isolated by magnetic sorting. Results show the mean plus or minus SEM of cell numbers from at least 3 mice in each group. *P < .05, compared with WT PBS. #P < .05, compared with SK-1-KO PBS. (B) CFSE-labeled EPCs injected intravenously into WT mice after kidney ischemia and visualized after 24 hours of reperfusion. Frozen tissue sections stained for CD31 (red) and DAPI (blue) allowed visualization of kidney vasculature as well as recruited CFSE-EPCs (green) by fluorescence microscopy. (C) mRNA levels of hsp70 and TLR4 were investigated in ischemic kidneys 24 hours after IRI by quantitative RT-PCR. Expression is normalized to their GAPDH gene, and results show the mean plus or minus SEM for 5 mice in each group. *P < .05, 1-way analysis of variance, compared with sham controls.