It is unknown whether the expression of these receptors is changed in IPF; CD44 is expressed on lung fibroblasts and epithelial cells [43], is induced in radiation- and bleomycin-induced pulmonary fibrosis [44] and in acute alveolar fibrosis [45], and is critical for resolution of noninfectious lung inflammation [46]. Here, CD44 is linked to idiopathic pulmonary fibrosis.