Our laboratory has previously shown that cardiac-specific overexpression of fibroblast growth factor 2 (FGF2 transgenic) results in increased recovery of contractile function and decreased infarct size following ischemia-reperfusion injury. Mitogen activated protein kinase (MAPK) signaling has been shown to be downstream of FGF2 and has been implicated in other models of cardioprotection. Treatment of FGF2 transgenic (Tg) and wildtype hearts with UO126, an MEK-ERK pathway inhibitor, significantly reduced recovery of contractile function following global, low-flow ischemia-reperfusion injury in FGF2 Tg hearts (86±2% vehicle-treated vs. 66±4% UO126-treated, p<0.05) but not wildtype hearts (61±7% vehicle-treated vs. 67±7% UO126-treated). Similarly, MEK-ERK inhibition significantly increased myocardial infarct size in FGF2 Tg (12±3% vehicle-treated vs. 31±2% UO126-treated, p<0.05) but not wildtype hearts (30±4% vehicle-treated vs. 36±7% UO126-treated). In contrast, treatment of FGF2 Tg and wildtype hearts with SB203580, a p38 inhibitor, did not abrogate FGF2-induced cardioprotection from post-ischemic contractile dysfunction. Instead, inhibition of p38 resulted in decreased infarct size in wildtype hearts (30±4% vehicle-treated vs. 11±2% SB203580-treated, p<0.05), but did not alter infarct size in FGF2 Tg hearts (12±3% vehicle-treated vs. 14±1% SB203580-treated). Western blot analysis of ERK and p38 activation revealed signaling alterations in FGF2 Tg and wildtype hearts during early ischemia or reperfusion injury. In addition, MEK-independent ERK inhibition by p38 was observed during early ischemic injury. Together these data suggest activation of ERK and inhibition of p38 by FGF2 is cardioprotective during ischemia-reperfusion injury.