Feline Stem Cell Factor (SCF) (also known as KIT ligand, KITLG, mast cell growth factor, or steel factor) is a cytokine and growth factor that plays a key role in hematopoiesis, stem cell maintenance, and immune cell development in cats (Felis catus). SCF belongs to a small group of hematopoietic growth factors that regulate survival and proliferation of stem and progenitor cells. It functions by binding to its receptor c-Kit (CD117), a receptor tyrosine kinase expressed on hematopoietic stem cells, mast cells, melanocytes, and germ cells, activating intracellular signaling pathways including PI3K/AKT, MAPK, and JAK/STAT that regulate cell survival, proliferation, and differentiation. In cats, SCF is produced by stromal cells, fibroblasts, endothelial cells, and epithelial cells and exists in both membrane-bound and soluble forms, which provide local and systemic regulation of c-Kit–expressing cells. SCF is particularly important for mast cell development and function, making it relevant to feline diseases such as mast cell tumors, where dysregulated c-Kit signaling contributes to abnormal mast cell proliferation. SCF also plays roles in hematopoietic stem cell maintenance, pigmentation biology, and reproductive cell development. Because of its central role in stem cell biology and c-Kit–mediated signaling, feline SCF is studied in research on hematopoiesis, mast cell disease, oncology, and regenerative medicine, contributing to understanding of growth factor regulation and cellular development in cats.