Evidences have described that Tim4 in macrophages could mediate p38 MAPK signaling pathway.33,34 Qin et al. demonstrated that Tim4 contributed to the epithelial to mesenchymal transition process and promoted nasal polyp formation via the ROS/p38 MAPK/Egr-1 pathway.34 Yeung et al. reported that inhibition of Tim4 expression reduced the expression of inflammatory cytokines through the p38 MAPK signaling pathways.35 Thus, p38 MAPK signaling pathway was taken into consideration to investigate the signal pathways of Tim4 in CD301b+ macrophages phenotype regulation. The gene discussed is EGR1; the disease is nasal cavity polyp.