Removal of atypical PKC blocks NGF-induced differentiation of PC12 cells.* We now examine the consequences that overexpression of atypical PKCs had upon NGF responses. PC12 cells were stably transfected with either PKC-ι or PKC-ζ. Overexpression of atypical PKCs markedly enhanced NGF- induced neurite outgrowth as well as enhanced NGF-stimulated JNK kinase. Cotransfection of HA-JNK1 along with increasing concentrations of PKC-ι, resulted in dose-dependent phosphorylation of GST c-Jun (1–79). NGF treatment of PC12 cells resulted in activation of NF-κB. In comparison, overexpression of atypical PKC-ι was by itself sufficient to activate NF-κB and shift the kinetics of NGF-induced κB activity. Furthermore, transfection of full-length antisense PKC-ι blocked basal and NGF-stimulated NF-κB. Differentiated and undifferentiated PC12 cells overexpressing atypical PKC-ι were protected from serum deprivation-induced cell death. Collectively, these findings demonstrate that atypical PKC-ι lies in a pathway that regulates NF-κB and contributes to both neurotrophin-mediated differentiation and survival signaling.