FPR2 and neoplasm: Coordinately, polarized TAMs secrete the antimicrobial peptide hCAP-18/LL-37, which consequently binds to its receptors (formyl peptide receptor 2 (FPR2) and P2X purinoceptor 7 receptor (P2X7R)) to enhance CSC self-renewal, invasion, and tumor-initiating properties [70].