TMPRSS2 and chronic obstructive pulmonary disease: TMPRSS2 expression is high in AT1, AT2, Transitional AT2, PNEC/ionocytes and club cells (Fig. 2b, Supplementary Fig. 5) and is slightly upregulated in the AT2 COPD samples (log2FC = 0.28, q value 0.04) (Supplementary Dataset 3), in contrast to a recent publication demonstrating decreased TMPRSS2 expression in severe COPD42.