The pathophysiology of septic shock is characterized by the induction of multiple proinflammatory genes and their products. Transcription factors play key roles in the transcription of these genes. Transcription factors may play important roles in the pathophysiology of septic shock. However, little information is available regarding the in vivo transcription factor activities during sepsis. We have studied the in vivo effects of LPS on the DNA binding activities of transcription factors Sp1 (promoter selective transcription factor), AP-2 (activating protein-2), AP-1 (activating protein-1), NF-kappaB (nuclear factor kappa B), and CREB (cAMF response element binding protein). We found that LPS up-regulated the DNA binding activity of inducible transcription factors AP-1, NF-kappaB, and CREB in a time-dependent manner, but downregulated the DNA binding activity of constitutive transcription factors Sp1 and AP-2. Thus, LPS regulates the inducible and constitutive transcription factors differentially under in vivo conditions.