CEACAM1 and pulmonary fibrosis: Carcinoembryonic antigen-related cell adhesion molecules (CEACAM)1+Msr1+Ly6C-F4/80-Mac1+ monocytes termed segregated-nucleus-containing atypical monocytes (SatM), share granulocyte characteristics, are regulated by CCAAT/enhancer binding protein β, and required for lung fibrosis by infiltrating into pulmonary interstitium (21).