CXCL1 and cancer: To address this question, we focused on: (1) soluble ICAM-1 (sICAM-1), whose elevated levels were connected to higher tumor aggressiveness in breast cancer patients [39,40,41]; (2) CCL2, the main inducer of monocyte migration to tumors, which is strongly connected to higher tumorigenicity in a large variety of cancers, breast cancer included [42,43,44,45,46,47,48]; (3) CXCL8 and CXCL1, two key inducers of neutrophil migration that are involved in regulating tumor progression [43,46,47,49,50].