In agreement with animal studies, significant upregulation of Rac1 GTPase and NOX activities has also been observed in patients with AF [114], whereas the use of diphenyleneiodonium and apocynin was shown to inhibit the production of superoxide via the inhibition of flavin-containing oxidases and of p47phox translocation, respectively [115]. The gene discussed is RAC1; the disease is atrial fibrillation.