MAPK3 and myocardial infarction: Consistent with reduced myocardial infarct size (Figure 6), hearts isolated from tamoxifen-treated Cre-ERT2/Gαi2fl-G184S/fl-G184S exhibited significantly enhanced postischemic recovery of developed pressure compared to hearts isolated from either vehicle-treated Cre-ERT2/Gαi2fl-G184S/fl-G184S mice or tamoxifen-treated Gαi2fl-G184S/fl-G184S mice that do not express Cre-ERT2 (Table 1).