Interestingly, sphingosine-1-phosphate (S1P) has been shown to be an important regulator of CCL2 expression in neuroblastoma, and preclinical studies suggest that inhibition of S1P2 leads to decreased CCL2 signaling and decreased macrophage infiltration in neuroblastoma tumors along with antitumor activity in vivo (172, 173). Here, CCL2 is linked to neuroblastoma.