PTGDR and asthma: In vivo studies showed that administration of a DP1 activator was protective in several models of inflammatory conditions including collagen-induced arthritis (Maicas et al., 2012), colitis (Ajuebor et al., 2000), atopic dermatitis (Angeli et al., 2004), asthma (Hammad et al., 2007), and chronic allergic lung inflammation (Maehara et al., 2019).