CCL2 and neoplasm: Another intriguing study revealed that the most downregulated gene classes in tumor endothelial cells involved antigen presentation (i.e., Major histocompatibility complex class I, II), immune cell homing molecules (i.e., ICAM-1), and chemotaxis related molecules (i.e., CCL2, CCL18, and IL6), which might explain how tumor cells gain immuno-tolerance (71).