|Cytokines are a large category of signaling molecules (~5–20 kDa) acting as immunomodulating agents for autocrine signaling, paracrine signaling, and endocrine signaling. These small proteins are produced by a broad range of cells, which include macrophages, B-Cells, T-Cells, basophils, mast cells, etc. The main cytokines consist of the ILs (Interleukins), the IFNs (Interferons), the TNFs (Tumor Necrosis Factors alpha and beta), and the growth hormone. The high interaction among cytokines often generates signal cascades leading to additive, synergistic, or antagonistic effects. Research has identified cytokines playing critical roles in regulating immunity, inflammation, hematopoiesis, neurogenesis, embryogenesis, oncogenesis, etc.