HMOX1 and acute respiratory distress syndrome: Heme oxygenase-1 (HO-1) has previously been reported to protect against ARDS [17, 18], and since diannexin has been shown to upregulate HO-1 expression [15, 16], we also evaluated the effect of an HO-1 inhibitor (zinc protoporphyrin, ZNPP) in the present study to better understand the role of diannexin in ARDS.