CD117, also known as c-Kit, is a receptor tyrosine kinase involved in cell growth, survival, and differentiation. It is expressed on various cell types, including hematopoietic stem cells, mast cells, melanocytes, and interstitial cells of Cajal in the gastrointestinal tract. CD117 plays a critical role in normal development and immune function, and its dysregulation is associated with several diseases, including cancers such as gastrointestinal stromal tumors (GIST) and acute myeloid leukemia (AML). Additionally, CD117 is a marker for cancer stem cells in some solid tumors and is targeted in cancer therapies.