SP1 and viral infectious disease: Through transcription factors such as NF-κB/REL complexes, p53, SP1, C-MYC, and AP-1, IEX-1 can be induced in a wide variety of cell types by irradiation, viral infection, inflammatory cytokines, chemical carcinogens, growth factors, and hormones (reviewed in 16), and C-MYC, NF-κB, and AP-1 are IPC responsive [31]; these transcriptional factors are likely to be involved in the immediate induction of IEX-1 by IPC.