In Nf1OPG mice, we elucidated a “neuron-immune-cancer cell” circuit [28], where T cells are induced by Nf1-mutant neuron-produced midkine to express Ccl4, which stimulates TAMs to secrete Ccl5, a key growth factor for Nf1-OPG development and progression [28, 53]. Here, CCL4 is linked to cancer.