Consistent with activation of the ERK1/2 cascade, BRAFV600E knock-in promoted an increase in expression of mRNAs for ERK1/2-dependent immediate early genes associated with cardiac hypertrophy (e.g. Egr1, Dusp5, Fos, Jun and Myc) [28,35,36], along with hypertrophic gene markers (Nppa, Nppb, Myh7) [2], consistent with cardiac hypertrophy (Figure 2F,G). Here, FOS is linked to cardiac hypertrophy.