RPL3L and cardiac hypertrophy: Indeed, transgenic mice overexpressing an activated form of mitogen-activated protein kinase kinase (MEK1; Figure 4A) or a constitutively active form of calcineurin (CnTG: Figure 4B), both of which exhibit significant cardiac hypertrophy by 3 months of age, showed prominent re-expression of the RPL3 protein and loss of RPL3L in the heart (Figures 4A, B).