Using a highly sensitive microarray-based approach, Lue et al. observed that miR-21 was increased in lung biopsy of IL-13 transgenic mice, with allergic inflammation, and demonstrated that miR-21 is responsible for decreased IL-12 expression, which would partially account for the exaggerated Th2 response seen in asthma (Figure 1) [26]. Here, IL13 is linked to asthma.