CXCR4 and neoplasm: There are two major distinct MIF-CD74 interactions; (1) Binding of MIF to CD74 can induce the recruitment of CD44 to the complex, which then activates non-receptor tyrosine kinases, leading ultimately to extracellular signal-regulated kinase phosphorylation and enhanced tumor growth in an autocrine manner or (2) MIF-CD74 complexes with the cysteine-X-cysteine (CXC) chemokine receptors CXCR2 on myeloid cells and CXCR4 on T cells thus influencing the M1/M2 polarization in intra-tumoral immune cells.