Our data support a role of Nedd4-2 in cellular SP-C trafficking in vivo, but genetic deletion of Sftpc did neither ameliorate (e.g., due to the deletion of a potentially toxic misprocessed proSP-C), nor aggravate (e.g., due to complete loss of SP-C) pulmonary fibrosis in conditional Nedd4-2−/− mice (Fig. 5). Here, SFTPC is linked to pulmonary fibrosis.