However, at 4 weeks of CKD, renal CD31 protein expression depended on the timing of HIF-2α transgene induction; it was significantly higher in transgenic CKD mice with later HIF-2α activation than in control mice as well as transgenic CKD mice with HIF-2α activation from the beginning of CKD induction. The gene discussed is PECAM1; the disease is chronic kidney disease.