SEMA3A and neoplasm: For example, tumor cells expressed relatively high levels of SEMA3A, PTN and MDK etc. Midkine (MDK), a heparin-binding growth factor that can promote tumor cell proliferation and EMT 44, while the corresponding receptors (SDC4, SDC2) were widely expressed in hypoxic cells (Macrophages_H, Neoplastic_H).