M2-polarized HMC3 microglia promoted tumor angiogenesis by releasing exosomal circKIF18A, and circKIF18A bound to its target gene FOXC2 that upregulated ITGB3, CXCR4, and DLL4 expressions and activated PI3K/AKT signaling54. The gene discussed is CXCR4; the disease is neoplasm.