2013) and that it has antimicrobial activity against bacteria and fungi (Noble et al. 2012; Nordin et al. 2012; Linge et al. 2013; Netsu et al. 2014; Nikaido et al. 2015). While these results suggest that midkine plays an important role in pulmonary inflammation, Zhang et al. (2015) has recently reported the role of midkine in acute respiratory distress syndrome (ARDS)‐associated lung fibrosis. Here, MDK is linked to pulmonary fibrosis.