AGTR1 and cardiac hypertrophy: Rac1cKI mice overexpressing AT1R developed a similar degree of hypertrophy as controls overexpressing AT1R at 2 and 4 months of age but a substantial exacerbation of cardiac hypertrophy was observed in Rac1cKI mice overexpressing AT1R at 6 months of age (Figure 5, A and B).