The SOCS3 (suppressor of cytokine signaling-3) protein is a 25 kD cytoplasmic protein that contains a SOCS box and an SH2 domain. SOCS3 has been shown to be involved the negative regulation of cytokine signaling via JAK/STAT pathway. SOCS3 has been shown to inhibit IL-2, IL-3, IL-4, IL-6, erythropoietin, prolactin, and growth hormone. SOCS3 has also been shown to regulate erythropoiesis in the fetal liver. SOCS3 is induced induced by inflammation, erythropoietin, GM-CSF, IL-10, and IFN-gamma. SOCS3 can be modified by JAK phophorylation which destabilizes the protein and ubiquitination which targets for destruction by the proteosome. SOCS3 has been shown to interact with the IGF-1 receptor, insulin receptor, gp130 receptor, erythropoietin receptor, leptin receptor, LIF receptor, JAK2, and elongin C. The SOC-25 monoclonal antibody recognizes human and mouse SOCS3 and has been shown to be useful for Western blotting.