Indeed, phosphorylation of ERK MAPK in AF was stimulated by TGFβ and this was prevented by exposure to 2 μM LY2109761, whereas exposure to 20 μM LY2109761 mimicked the effect of TGFβ, causing a similar level of ERK phosphorylation (Fig. 7D). Here, TGFB1 is linked to atrial fibrillation.