The TBC1D8 protein is a member of the TBC domain family and functions as a GTPase-activating protein (GAP) that negatively regulates the activity of small G proteins of the Rab family, participating in the fine-tuning of intracellular vesicle transport and signal transduction. This protein has garnered significant attention in reproductive and cancer research. Studies have shown that TBC1D8 is a key determinant of oocyte maturation and female fertility, with defects in its expression leading to embryonic development arrest. Moreover, TBC1D8 is abnormally overexpressed in various cancers (such as breast and lung cancer), where it acts as an oncogene by modulating signaling pathways related to cell proliferation, invasion, and metastasis (e.g., the EGFR/Ras pathway). Thus, it serves as a potential biomarker for disease diagnosis and a therapeutic target.