SCGB1A1 and idiopathic pulmonary fibrosis: To gain insight into the identity of the corresponding CD274pos population in the human lung, four donor and four IPF epithelial populations were sorted according to their HTII-280 vs. CD274 expression pattern (Figure 3A, populations Q1—HTII-280pos CD274neg, Q3—HTII-280pos CD274pos and Q4—HTII-280neg CD274neg), and the expressions of the SFTPC and SCGB1A1 lineage-specific markers were determined in these isolated subpopulations by qPCR (Figure 3B).