CCL2 and neoplasm: The addition of macrophages to the PanNET microenvironment has been found to increase the expression of cytokines and chemokines, such as IL-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α) in tumor cells, and to promote tumor progression and immunosuppression in the tumor microenvironment14.