SLCO1B3 encodes organic anion transporting polypeptide 1B3 (OATP1B3), a hepatic membrane transporter mediating sodium-independent uptake of diverse organic anions 1. The transporter exhibits broad substrate specificity, including bile acids (taurocholate), conjugated steroids, eicosanoids, thyroid hormone (T4), and clinically important drugs such as statins, methotrexate, and paclitaxel 2. OATP1B3 functions as a significant bile acid uptake transporter comparable in capacity to NTCP, with bicarbonate serving as the probable counteranion 3. The transporter displays pH-sensitive substrate specificity toward sulfated steroids and bile acids, with enhanced activity in acidic microenvironments 1. Hepatic OATP1B3 mediates drug clearance and bilirubin glucuronide detoxification, establishing it as essential for drug elimination 3. Polymorphic variants reduce drug clearance and increase adverse effects, including statin-induced rhabdomyolysis and altered digoxin pharmacokinetics 4. Aberrant extrahepatic SLCO1B3 expression promotes chemotherapy resistance across multiple cancer types, including breast, prostate, and hepatic cancers, and supports immune evasion in intrahepatic cholangiocarcinoma 5. SLCO1B3 dysfunction associates with Rotor-type hyperbilirubinemia. These properties position SLCO1B3 as critical for both normal hepatic physiology and disease pathogenesis.