EPHA3 and idiopathic pulmonary fibrosis: EphA3 was abundantly expressed in cultured IPF lung fibroblasts (Supplemental Figure 5A), and the addition of preclustered Ephrin A5–Fc (EFNA5-Fc) to these cells strongly promoted the phosphorylated EphA3 receptor, indicating the activation of this receptor (Supplemental Figure 5B).