Comparison of these DEGs to DEGs between RA- and CS-exposed mouse lung AT2 cells identified two overlapping genes, NUPR1 and CD74. NUPR1, a cellular stress response gene and positive regulator of  antioxidants33,34, had the largest reduction in AT2B expression in COPD (fold change (fc) = 0.35) and was also decreased in AT2 cells from mice exposed to CS (fc = 0.51) (Fig. 3B, C). Here, CD74 is linked to chronic obstructive pulmonary disease.