ABSTRACT
Inhibitor of differentiation (Id) is a member of the helix-loop-helix protein family and exerts negative transcriptional regulation by forming heterodimers with other HLH proteins to inhibit gene expression. Id can promote cell proliferation and inhibit cell differentiation. Especially, Id plays an essential role in the development and differentiation of various immune cells. This review mainly introduces the latest research progress in how members of the Id family regulate the generation and fate determination of multiple cell lineages in the innate and adaptive immune systems. By interacting with different transcription factors such as E protein, Id has a variety of functions in the differentiation process of natural killer cells, innate lymphoid cells, T cells, and B cells, etc., ensuring the well-coordinated development of immune cells in various immune organs. On the other hand, the abnormal expression and functional deficiency of the Id gene are closely related to the occurrence and progression of hematologic malignancies. In different hematologic malignancies ranging from leukemia to malignant lymphoma, Id plays diverse roles as a cancer-promoting or tumor suppressor factor. Therefore, Id can be used as a marker for the diagnosis and prognosis of hematologic malignancies and has the potential to become an important target for cancer therapy.