Macrophage-specific, but not intestinal epithelial cell-specific Slco2a1 knockout increased the susceptibility to DSS-induced colitis, partially phenocopying systemic Slco2a1-deficient mice, which indicated that Slco2a1 in macrophages might play an important role in maintaining mucosal homeostasis in conditions of injury. The gene discussed is SLCO2A1; the disease is colitis.