SFTPC and viral infectious disease: Surprisingly, when Tmx was injected after viral infection, we observed 7.9% ± 1.4% Trp63CreERT2 lineage-labeled cells expressed the AT2 cell marker SftpC but not p63 or Krt5 in the areas that surrounded the injured foci, and the number was increased to 19.4%±4.2% in Trp63CreERT2;Trpm5-/-;R26Ai14 mice (Figure 5A and Figure 5—figure supplement 1C).