PF543 may impact SPHK1 signaling in all these cell types involved in the pathobiology of pulmonary fibrosis since SPHK1 is present in all mammalian cells and generates S1P that can act via its receptors on different types of target cells through diverse mechanisms involving vascular permeability, inflammatory cell infiltration, fibroblast migration, and fibroblast to myofibroblast differentiation. The gene discussed is SPHK1; the disease is pulmonary fibrosis.