T-5224 is a selective inhibitor of c-Fos/activator protein-1. T-5224 ameliorates liver injury and improves survival through decreasing production of proinflammatory cytokines and chemokines in endotoxemic mice. T-5224 has been investigated in phase II human clinical trials. T-5224 may be a promising new treatment for septic kidney injury. Activator protein 1 (AP-1) is a pivotal transcription factor that regulates a wide range of cellular processes including proliferation, apoptosis, differentiation, survival, cell migration, and transformation. Accumulating evidence supports that AP-1 plays an important role in several severe disorders including cancer, fibrosis, and organ injury, as well as inflammatory disorders such as asthma, psoriasis, and rheumatoid arthritis.