Mutation in SFTPA1 resulted in IPF in a consanguineous Japanese family, and SFTPA1 knock-in (Sftpa1-KI) mice spontaneously developed pulmonary fibrosis with increased necroptosis derived by c-Jun N-terminal kinase (JNK)-mediated upregulation of RIPK3 in AEC2s. Here, SFTPA1 is linked to pulmonary fibrosis.