Although this relative blank area is spread throughout the tumor tissue, the distribution of cells is not absolutely uniform, because in addition to CSF1, CCL2, CCL3, CCL4, CCL5, CCL20, CCL18 and CSF-2 may play the role of recruitment to macrophages, and due to the difference of action threshold and cytokine concentration [20]. Here, CCL2 is linked to neoplasm.