Erythropoietin levels decrease with CID administration. Six mice (depicted in Figure 4) were used as samples to measure erythropoietin levels in CID-treated and control mice. RBC numbers were measured 10 weeks after the last CID administration; RBC numbers and the percentage of GFP-positive RBCs had fallen to baseline (A-B, baseline). Three of the 6 mice were treated with 10 μg/kg CID 3 days a week for 2 weeks, then every day for 2 weeks, at which time all mice were killed (week 67 after transplantation). (A) Erythrocyte numbers and the percentage of GFP-positive erythrocytes increased in CID treated mice (+) relative to untreated mice (-). (B) Erythropoietin levels were measured in the 6 mice, 3 CBA/N mice, and 3 CBA-Pk-1^slc/Pk-1^slc mice (PK-/PK-). Treated mice had erythropoietin levels between those of CBA/N mice and those of CBA-Pk-1^slc/Pk-1^slc mice. ^*Data from 1 of the untreated mice with an erythropoietin level of 570 mU/mL was not included in the bar chart.