LEP and plasma cell myeloma: Indeed, adipocyte-derived factors such as monocyte chemoattractant protein 1 (MCP-1) and stromal cell-derived factor 1 (SDF1) are known chemotactic factors for myeloma cells (9, 23), whereas other factors promote myeloma proliferation (e.g., leptin) (10) and resistance to chemotherapies (e.g., leptin and adipsin) (11).