Suppressors of cytokine signaling (SOCS) regulate receptor function. (A) Insulin binding results in phosphorylation of the receptor and subsequent phosphorylation of IRS-1. These processes initiate the insulin-signaling pathway. (B) SOCS proteins disrupt interactions of components of the insulin-signaling pathway by binding phosphorylated proteins and thereby inhibiting the pathway. The binding of a signal component by SOCS results in proteasomal degradation in some cases. (IRS-1, insulin-receptor substrate 1; SOCS, suppressor of cytokine signaling.)