CXCL1 and myocardial infarction: Conversely, the chemokines in the infarcted hearts showed different kinetics: the levels of KC (CXCL1) and MCP-1 increased by ~10-fold and ~60-fold, respectively, on day 1 after MI compared with those in the sham group; whereas KC had already decreased by day 3, MCP-1 remained at a high level on day 3 after MI.