SLCO1A2 encodes organic anion-transporting polypeptide 1A2 (OATP1A2), a sodium-independent transporter mediating cellular uptake of diverse organic anions at the plasma membrane. Primary substrates include bile acids (cholate, taurocholate, glycocholate) 1, steroid sulfates (DHEAS, estrone-3-sulfate) 23, all-trans-retinol for visual cycle maintenance 4, thyroid hormones (T3, T4) 15, and prostaglandin E2 1. SLCO1A2 mediates apical uptake across intestinal epithelial cells and retinal pigment epithelium, with expression regulated by vitamin D receptor signaling 6 and suppressed by TNFα-NFκB signaling 7. Clinically, SLCO1A2 transports methotrexate and other chemotherapeutic drugs 8. Loss-of-function variants (E184K, D185N, T259P, D288N) impair membrane expression and reduce transport of estrone-3-sulfate, imatinib, and methotrexate by 20-50% 8, associating with increased methotrexate toxicity risk in rheumatoid arthritis patients 9. Genetic variants in SLCO1A2 show associations with late-life cognitive outcomes in APOE-ε4 carriers 10 and progressive supranuclear palsy susceptibility 1112, suggesting broader roles in neurological function beyond drug transport.