ABCG2 and systemic lupus erythematosus: ABCB1: multidrug resistance protein; ABCC2: multidrug resistance-associated protein; ABCG2: breast cancer resistance protein; ANCA: antineutrophil cytoplasmic antibody; CYP: cytochrome P450; HC: healthy control; NA = not applicable; SLCO1A2: organic anion transporting polypeptide; SLE: systemic lupus erythematosus; SVV = small vessel vasculitis; UGT = uridine diphosphate glucuronosyltransferase.