In his letter, Dr. Pick criticizes our use of relative values when representing the NOX2 inhibitory action of a novel small molecule (GSK2795039) in a semi-recombinant NOX2 membrane assay. To address this concern, we performed additional experiments using the superoxide inhibitable assays cytochrome C and water soluble tetrazolium salt (WST-1) reduction. In this letter, we document turnover values between 80 and 100 mol O2(•-)/s/mol cytochrome b558 in our semi-recombinant assay and confirmed that GSK2795039 inhibits the NOX2 isoform in the submicromolar range. Antioxid. Redox Signal. 23, 1251-1253.