The invention relates to the field of glycoprotein processing in transgenic plants used as cost efficient and contamination safe factories for the production of recombinant biopharmaceutical proteins or pharmaceutical compositions comprising these glycoproteins. The invention provides a plant comprising a functional mammalian enzyme providing mammalian GnTIII that is normally not present in plants, said plant additionally comprising at least a second mammalian protein or functional fragment thereof that is normally not present in plants.