Western blot using affinity purified anti-NAG-1/GDF15 (N-terminal specific) antibody shows detection of a 14 kDa band corresponding to recombinant human NAG-1 purified from CHO cells. Samples were electrophoresed on a 4-20% gradient gel under reducing conditions. Lane 1 shows NAG-1 detection. Lane 2 shows reactivity is greatly diminished when this antibody is preincubated with the immunizing peptide prior to Western blotting.