“pH … folate uptake was markedly reduced by inhibitors of anion exchange (4,4'-diisothiocyano-…,2'-disulfonic acid stilbene; 4-acetamido-4-isothiocyanostilbene-2,2'-disulfonic acid; furosemide ), and was saturable (folate Km = 0.19 +/- 0.02 microM; Vmax = ….8 +/- 0.4 pmol X mg protein-1 X min-1).”