F Single-cell transcriptomic data from aging tissues in the mouse lung from Tabula Muris Senis. Upper left panel: uniform manifold approximation and projection (UMAP) of cell identity with ATII cells represented as red dots. Upper right panel: dot plot of Ace2 expression according to age (young = 3 months; old = 30 months). Dot size represents fraction of cells expressing a given gene. Lower panel: UMAP of Ace2 expressing cells depicted as blue dots. 