CD99

CD99, also known as MIC2, is a cell surface glycoprotein encoded by the CD99 gene in humans. It has a transmembrane structure and includes a signal peptide, extracellular region, transmembrane region, and cytoplasmic region. CD99 plays a role in various biological processes, including cell adhesion, cell migration, cell death, immune processes, and other key processes related to inflammation, tumors, and cancer. It plays a role in the activation and differentiation of T cells and the differentiation of dendritic cells, and may be involved in regulating the signaling of TCR and costimulatory molecules. CD99 may also be involved in the signaling pathways of cell adhesion and migration, as well as the induction of Ewing sarcoma cell death through the IGF-1R/RAS/Rac1 signaling pathway. CD99 functions differently in different types of cancer, sometimes as a tumor suppressor, and sometimes as a carcinogenic factor. It is up-regulated in some cancers, such as Ewing sarcoma, while down-regulated in other cases, such as plasma cell tumors. Therefore, CD99 has become a potential target for the treatment of certain cancer types, especially in Ewing sarcoma and T-cell acute lymphocytic leukemia. Targeting CD99 or its interacting signaling pathways provides new ideas for developing new cancer treatment strategies, especially in the field of cancer immunotherapy, which has shown its importance.