FPR2 and neoplasm: Some special SAA1 subtypes such as SAA1.1 and SAA1.3 can inhibit tumor metastasis by inducing tumor cell apoptosis and inhibiting angiogenesis 19; SAA1 is mediated by activating ERK and formyl peptide receptor-like-1 (FPRL1) Signaling pathways to increase expression of matrix metalloproteinases in monocytes, regulate inflammation and immune responses and promote metastatic growth of tumor cells20; SAA1 can also promote tumor cell migration by inducing adhesion molecule expression, angiogenesis, and matrix degradation 21.