It appears that our strain (5-month-old Prdm16flox/flox; Myh6-Cre) progresses to cardiac hypertrophy earlier than 9-month-old Prdm16flox/flox; Mesp1-Cre mice, consistent with the other conditional strain (Prdm16flox/flox; αMHCMerCreMer/+) developing cardiac hypertrophy as early as age 3 months [13]. This evidence concerns the gene MESP1 and cardiac hypertrophy.