Since Prrx1 loss of function is associated with perinatal lethality in Prrx1-/- pups (Ihida-Stansbury et al., 2004; Lu et al., 1999; Martin et al., 1995), we sought first to evaluate Prrx1 function during lung fibrosis using Prrx1+/- +/- mice. This evidence concerns the gene PRRX1 and pulmonary fibrosis.