SDF4 and gastric cancer: The median serum SDF4 levels in GC patients increased with clinical stage, and were 266.2 pg/ml (range, 70.4–1202 pg/ml), 303.4 pg/ml (range, 39.1–1353.1 pg/ml), 326.6 pg/ml (range, 84.1–808.8 pg/ml), and 455.1 pg/ml (range, 92.8–3185.3) in patients at clinical GC stages I, II, III, and IV, respectively (Fig. 1b).