PLXNA4 and pulmonary fibrosis: It has been empirically demonstrated that lncRNA prostate cancer-associated transcript 29 (PCAT29) inhibits the miRNA-221-mediated RASAL1/ERK1/2 signaling pathway downstream of transforming growth factor β1 (TGF-β1) in lung fibroblasts, thus suppressing certain proinflammatory cytokines associated with lung fibrosis, such as N4bp2 and Plxna4, and ultimately slowing the progression of pulmonary fibrosis (Liu et al., 2018).