On the other hand, GFP-p105 (GFP-p50 with IkappaB gamma) localized only in the cytoplasm before stimulation and translocated to the nucleus with stimulant specificity similar to that of native NF-kappaB/IkappaB.     ///    It was suggested that this might be due to the existence of a limiting step where NF-kappaB is released from NF-kappaB/IkappaB by the proteasome.. 