Suppressor of cytokine signaling (SOCS) family proteins are involved in a negative feedback system that regulates cytokine signal transduction. SOCS-3 is involved in negative regulation of cytokines through the JAK/STAT signaling pathway by binding to tyrosine kinase receptors including gp130, LIF, erythropoietin, insulin, IL-12, GCSF and leptin receptors. Genetic variation in the promoter region of SOCS-3 is associated with susceptibility to atopic dermatitis 4 (eczema).
Breast cancer type 1 susceptibility protein (BRCA1) plays a central role in DNA repair by facilitating cellular response to DNA repair. BRCA1 is required for appropriate cell cycle arrests after ionizing irradiation in both the S-phase and the G2 phase of the cell cycle. BRCA1 is part of the BRCA1-associated genome surveillance complex (BASC), which contains BRCA1, MSH2, MSH6, MLH1, ATM, BLM, PMS2 and the RAD50-MRE11-NBS1 protein complex. Defects in BRCA1 are a cause of genetic susceptibility to breast and ovarian cancers.