Previous studies have shown that activation of the SEMA3–PLXNA–NRP axis is reduced in monocyte–endothelium interactions, although SEMA3A–NRP1 binding could sustain directed migration of macrophages under hypoxic condition in tumour tissues.4,30 Up-regulation of these receptors could sensitise the response of macrophages to the guidance signals provided by Class III semaphorins. This evidence concerns the gene NRP1 and neoplasm.