C-C motif chemokine ligand 2 (CCL2), also known as monocyte chemoattractant protein-1 (MCP-1). CCL2 is a small cytokine that plays a critical role in recruiting immune cells, particularly monocytes and macrophages, to sites of inflammation, infection, or injury. In cancer, CCL2 is often overexpressed in the tumor microenvironment and promotes tumor growth, angiogenesis, and metastasis by recruiting tumor-associated macrophages (TAMs) that suppress anti-tumor immunity. In fibrotic diseases like IPF, CCL2 drives the recruitment of profibrotic monocytes and macrophages that contribute to excessive collagen deposition and tissue scarring.