CXCR2 and inflammatory bowel disease: In addition to our findings in PAI-1 KO mice and the abovementioned PCR array data, these results suggest that PAI-1 plays an essential role in IBD, primarily by upregulating the expression of CXCL1/CXCL5, which subsequently promotes neutrophil infiltration via the CXCL1/CXCL5/CXCR2 pathway and colon injury.