PDPN and influenza: Cdh5CreERT2; ROSA26LSL-tdTomato; Atf3lox/lox (Atf3EC-KO) and control Cdh5CreERT2; ROSA26LSL-tdTomato (Atf3EC-WT) mice were subjected to influenza injury and assessed at 14 and 21 dpi for PDPN expression to define alveolar architecture (Figure 3A, Figure 3—figure supplement 1).