NFKB1 and major depressive disorder: For example, ROS are able to activate nuclear factor kappa B (NF-κB) by decreasing binding affinity of the inhibitory subunit, Iκ-B, to NF-κB, an observation made relevant by the fact that NF-κB activity has been demonstrated to increase with aging and depression (Toliver-Kinsky et al., 1997; Koo et al., 2010).