Mouse GM-CSF (Granulocyte–Macrophage Colony-Stimulating Factor, CSF2) is a hematopoietic cytokine belonging to the colony-stimulating factor family, which also includes G-CSF (CSF3) and M-CSF (CSF1) that regulate the development, proliferation, and activation of myeloid immune cells. In mice (Mus musculus), GM-CSF is produced by activated T lymphocytes, macrophages, endothelial cells, fibroblasts, and epithelial cells in response to infection, inflammatory cytokines, or immune stimulation. Mouse GM-CSF binds to the GM-CSF receptor (CSF2R) expressed on hematopoietic progenitor cells and mature myeloid cells, activating intracellular signaling pathways such as JAK/STAT, MAPK/ERK, and PI3K–AKT, which promote the proliferation and differentiation of granulocytes, macrophages, and dendritic cells, as well as enhance their immune effector and antigen-presenting functions. In murine immunity, GM-CSF plays a critical role in regulating inflammatory responses and development of antigen-presenting cells. Mice are widely used as animal models for studying immune regulation and inflammatory disease, and GM-CSF has been extensively studied in mouse models of autoimmune diseases such as experimental autoimmune encephalomyelitis (EAE), a widely used animal model for human multiple sclerosis, where GM-CSF produced by T cells drives pathogenic myeloid cell activation and central nervous system inflammation, providing key insights into immune-mediated neuroinflammatory disease mechanisms.