The causative role of SPHK1 in PF was confirmed in genetically engineered mice lacking Sphk1. Bleomycin upregulated the expression of SPHK1 in lungs compared to WT mice, and genetic deletion of Sphk1, but not Sphk2, attenuated bleomycin-induced mortality, lung injury and collagen deposition in the lungs. Here, SPHK1 is linked to pemphigus foliaceus.