CXCR2 and ulcerative colitis: These tests assess the messenger RNA (mRNA) expression of five biomarkers, including the inflammatory marker C-X-C Motif Chemokine Receptor 2 (CXCR2) and four genes linked to ulcerative colitis: cyclin-dependent kinase 1 (CDK1), midkine (MDK), insulin-like growth factor binding protein 5 (IGFBP5), and Homeobox A13 (HOXA13) [42].