Abstract
Introduction: Depending on their polarization, myeloid cells can either promote or restrain tumor progression. By secreting myelopoietic factors tumours promote myeloid cells polarization toward a phenotype that provides immune protection and that stimulate neoplastic cells growth, invasiveness, and metastasis. Chemokines and their cognate receptors are thought to play a key role in myeloid cell trafficking, however, their study in vivo is hindered by their signal redundancy and integration.