Further analysis revealed that there were more BM-derived cells which co-expressed PDGFRβ in Sca-1+ than Sca-1− chimeric hearts, and the number of GFP/PDGFRβ double-positive cells increased in Sca-1+ but not Sca-1− chimeric hearts after MI. The gene discussed is PDGFRB; the disease is myocardial infarction.