MDK and neuroblastoma: An explanation is posited in the study published by Takei et al in which it was shown that the functional loss of midkine in rectal carcinoma cells leads to a reduction in cell proliferation in vitro and of primary tumor growth in the mouse model.16 An association between S‐MK and survival was also shown for patients with neuroblastoma and esophageal cancer.13, 32 A recent study of Ito et al evaluated the diagnostic impact of S‐MK in patients with gastric adenocarcinoma.