CCL2 and cancer: The role these and other metabolic factors play in cancer and cancer-related co-morbidities is coming into focus as the research community begins to examine them in addition to long-standing candidates from the immune system such as cytokines [e.g., interleukin (IL)-1β, IL-6, TNF-α] and chemokines (e.g., CCL2, CXCL12).