ABCB5 is an ATP-binding cassette transporter that functions as an energy-dependent efflux pump mediating multidrug resistance 1. The full-length ABCB5 protein (1257 amino acids) contains two transmembrane domains and two nucleotide-binding domains, conferring 1.5-3 fold resistance to taxanes and anthracyclines through reduced intracellular drug accumulation 1. Beyond chemoresistance, ABCB5 marks and is essential for limbal stem cell (LSC) maintenance; ABCB5-positive LSCs are required for corneal development and repair, with ABCB5 knockout mice showing defective corneal differentiation and impaired wound healing 2. ABCB5+ mesenchymal stem cells (MSCs) demonstrate therapeutic potential in regenerative medicine, including wound healing and angiogenesis; in clinical trials, topically applied ABCB5+ MSCs reduced diabetic foot ulcer surface area by 59-67% at 12 weeks without adverse events 3. Mechanistically, ABCB5 upregulates cellular glutathione levels independent of direct glutathione transport, enhancing cellular antioxidant defense 4. In hematologic malignancies, ABCB5 expression correlates with drug resistance and poor prognosis, particularly in acute lymphoblastic leukemia and acute myeloid leukemia 5. Recent genetic studies suggest ABCB5 may contribute to early neurological outcomes after ischemic stroke 6.