The JAK-STAT signaling pathway is a chain of interactions between proteins in a cell, and is involved in processes such as immunity, cell division, cell death and tumor formation. The pathway communicates information from chemical signals outside of a cell to the cell nucleus, leading to the activation of genes through transcription. There are three key components in the JAK-STAT signaling: Janus kinases (JAKs), signal transducer and activator of transcription proteins (STATs), and receptors (which bind the chemical signals). Disregulated JAK-STAT signaling may lead to a variety of diseases, such as skin conditions, various cancers, and disorders affecting the immune system.