SLC43A3 encodes equilibrative nucleobase transporter 1 (ENBT1), a sodium-independent membrane transporter that mediates bidirectional transport of purine nucleobases across cell membranes 1. The protein facilitates equilibrative transport of adenine and serves as the primary transporter for the chemotherapeutic agent 6-mercaptopurine (6-MP) in human cells 1. SLC43A3 expression levels directly correlate with 6-MP uptake rates and cytotoxicity in acute lymphoblastic leukemia cell lines, with higher expression associated with greater drug sensitivity 1. Beyond nucleobase transport, SLC43A3 functions as a regulator of fatty acid flux, promoting fatty acid efflux while inhibiting uptake in adipocytes 2. The transporter shows increased expression following bariatric surgery and during adipocyte differentiation 2. In intervertebral disc degeneration, SLC43A3 expression is negatively correlated with intracellular lipid content, and its overexpression alleviates palmitic acid-induced cellular stress and senescence 3. Clinically, SLC43A3 serves as a potential biomarker for 6-MP therapeutic efficacy in leukemia treatment and for 6-thio-2'-deoxyguanosine sensitivity in non-small cell lung cancer 14. The transporter is expressed in gastrointestinal tract, bone marrow, liver, and brain microvessels, with functional conservation between human and murine orthologs 56.