when the cells are incubated at 37 degrees c in the presence of a fluorescein-labeled neoglycoprotein , the fluorescence intensity of a cell is low because of the low ph of endosomes and lysosomes but is increased upon a postincubation at 4 degrees c in the presence of monensin , a proton/sodium ionophore .
C0007634
the
C0024369
lysosomes