SOCS family proteins form part of a classical negative feedback system that that regulates cytokine signal transduction. SOCS1 is involved in negative regulation of cytokines that signal through the JAK/STAT3 pathway. Through binding to JAKs it inhibits their kianse activity. In vitro, they also supresses Tec protein-tyrosine activity. SOCS1 appears to be a major regulator of interleukin 6 (IL6) and leukemia inihibitory factor (LIF) signaling. SOCS-1 regulates interferon-gamma mediated sensory neuron survival. It is also implicated, through SOCS box binding, in ubiquitin-dependent protein degradation. There is high expression in thymus, and lower expression in lung and spleen.