Active CAMKIIα is sufficient for Nox5 activation. A, COS-7 cells were cotransfected with HA-Nox5 and either control (lacZ) or WT CAMKIIα cDNAs, and basal superoxide release was measured. Cell lysates were immunoblotted for total Nox5 and CAMKIIα (bottom). B, COS-7 cells were cotransfected with HA-Nox5 and either control (lacZ) or WT CAMKIIα in the presence and absence of KN-93 (10 μM). Basal superoxide release was measured with L-012. Cell lysates were immunoblotted for total Nox5 (bottom). Results are presented as the mean ± S.E.M., n = 5. *, p < 0.05 versus vehicle or control lacZ. C, COS-7 cells were cotransfected with HA-Nox5 and either control (lacZ), WT CAMKIIα, dominant-negative CAMKIIα (DN, T305D), or constitutively active-CAMKIIα (CA, T286D). Basal superoxide release was measured using L-012, and cell lysates were immunoblotted for total Nox5 (bottom). Results are presented as mean ± S.E.M. (n = 4–6); *, p < 0.05 versus control (lacZ); #, p < 0.05 versus WT CAMKIIα.