IL13 and fibrosis: Contrary to previous studies suggesting a pro-fibrotic role, two contrasting studies, one using a fibrosis model with transgenic mice expressing IL-13 (Lanone et al., 2002) and the other a model involving radiation injury followed by bone-marrow transfer (so-called ‘RAD+BMT’) (England et al., 2011), observed either no effect or an anti-fibrotic effect of MMP-12, respectively.