SH2B3 (SH2B Adaptor Protein 3): SH2B3 (SH2B Adaptor Protein 3) is an adaptor protein that negatively regulates cytokine signalling in haematopoietic cells. It plays a key role in maintaining haematopoietic stem cell homeostasis and controlling immune responses. Mutations in SH2B3 are linked to various haematological disorders, including myeloproliferative neoplasms and autoimmune diseases, highlighting its importance in blood cell development and immune regulation.