For example, a comparative study of human lung sections from healthy donors and donors with idiopathic pulmonary fibrosis (IPF) showed that healthy donors expressed PAR2 in alveolar macrophages and alveolar type 2 cells, while those of the IPF donors expressed PAR2 in hyperplastic alveolar type 2 cells and fibroblasts [37]. This evidence concerns the gene F2RL1 and pulmonary fibrosis.