For example, MDK (ligand) and NCL (receptor) were highly expressed in the tumor microenvironment (TME) of recurrent samples (Figure 5E), consistent with previous studies implicating the roles of this ligand–receptor pair in tumorigenesis (36, 37) and the MK-deficiency-reduced tissue infiltration of microglia (38). The gene discussed is MDK; the disease is neoplasm.