Inhibition of FUT8 in human Hep5-positive cells at 100 uM using (S)-2-(((9H-fluoren-9-yl)methoxy)carbonylamino)-4-((2R,3R,4R,5S,6R)-3-acetamido-5-((2S,3R,4R,5S,6R)-3-acetamido-5-((2S,3S,4S,5R,6R)-4-((2R,3S,4S,5S,6R)-3-((2S,3R,4R,5S,6R)-3-acetamido-4,5-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)-4,5-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)-6-(((2S,3S,4S,5S,6R)-3-((2S,3R,4R,5S,6R)-3-acetamido-4,5-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)-4,5-dihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)methyl)-3,5-dihydroxytetrahydro-2H-pyran-2-yloxy)-4-hydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)-4-hydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-ylamino)-4-oxobutanoic acid as substrate after 24 hrs in presence of GDP-fucose by HPLC method relative to control