SULT1C4 encodes a cytosolic sulfotransferase that catalyzes the sulfate conjugation of diverse xenobiotic and endogenous compounds using 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as a sulfonate donor 1. The enzyme demonstrates unique substrate specificity, being the only human SULT capable of sulfating the chemotherapeutic anthracyclines doxorubicin and epirubicin 1. SULT1C4 also metabolizes the tramadol metabolite O-desmethyltramadol with high catalytic efficiency, being 60 times more efficient than SULT1A3 2. The enzyme exhibits regioselective activity, preferentially producing genistein 7-sulfate from the dietary flavonoid genistein 3. SULT1C4 shows distinct developmental expression patterns, with multiple transcript variants expressed at higher levels in prenatal versus postnatal liver, though protein levels remain low due to the predominant transcript variant producing minimal stable protein 4. Genetic polymorphisms in SULT1C4 significantly affect doxorubicin sulfation activity among different allozymes 5 and influence the excretion of phase II flavanone metabolites following citrus consumption 6. In hepatocellular carcinoma, SULT1C4 expression is altered and associated with immune infiltration 7, suggesting potential roles in cancer metabolism and therapeutic response.