However, while EPO treatment increased expression of these heart failure-associated genes in WT mice, EPO treatment did not change expression of heart failure-associated genes Cdk8, TGFβ2, and NOX4 and hypertrophic cardiomyopathy-related genes Nppa in nNOS−/− mice (Figures 4A, B). The gene discussed is NOX4; the disease is hypertrophic cardiomyopathy.