Humans NF-kappa B article human human cell immunoglobulin enhancer binding protein NF-κB priority journal protein expression transactivation tumor necrosis factor alpha Hela Cells Transcription Factor RelA Transcription Factors Transfection Tumor Necrosis Factor-alpha controlled study cytoplasm enzyme activity genetic transfection p38 Mitogen-Activated Protein Kinases protein analysis protein binding synaptophysin transcription factor transcription regulation Apoptosis Binding Sites Binding, Competitive Blotting, Western