Chia et al. (2018) showed that, whilst CSF-1 played a role in macrophage recruitment, signalling to Cxcr4 was absolutely required for the recruitment of macrophages to the Akt-transformed brain in zebrafish tumour initiation, and that PNC-derived Cxcl12 was the major ligand for this interaction [142]. The gene discussed is CXCR4; the disease is neoplasm.