The pIκB-EGFP Vector encodes the IκB-EGFP Signaling Probe, which is a fusion of enhanced greenfluorescent protein (EGFP) and IκB. IκB is an inhibitor of NFκB, a transcription factor involved in theimmune response and inflammatory diseases. When the NFκB pathway is inactive, IκB and NFκBexist as an inactive complex in the cytosol. Upon stimulation, IκB is degraded. In cells transfectedwith pIκB-EGFP, degradation of the IκB-EGFP fusion protein is observed as a decrease in EGFPfluorescence (1). The IκB-EGFP Signaling Probe is constitutively expressed and resides in thecytosol.EGFP is a red-shifted, human codon-optimized variant of GFP (2–6) that has been engineered forbrighter fluorescence and higher expression in mammalian cells. Its excitation maximum is 488 nmand emission maximum is 509 nm. For more information on the properties of EGFP, please refer tothe BD Living Colors? User Manual (PT2040-1) included with the vector.Expression of the IκB-EGFP is driven by the human CMV immediate-early promoter. The SV40 poly-Asequence directs proper processing of the 3' end of the fusion construct. The vector backbone alsocontains an SV40 origin for replication in mammalian cells expressing the SV40 T-antigen. Aneomycin resistance cassette (Neor) allows kanamycin selection in E. coli and neomycin (G418)selection in eukaryotic cells. This cassette consists of the SV40 early promoter, the neomycin/kanamycin resistance gene of Tn5, and poly-A signals from the Herpes simplex virus thymidinekinase (HSV TK) gene. The vector backbone also provides a pUC origin of replication forpropagation in E. coli and an f1 origin for single-stranded DNA production.