SRF and cardiac hypertrophy: We observed that approximately 1/10 of the recently identified 578 miRNAs are highly expressed in the mouse heart; SRF overexpression in the mouse heart resulted in altered expression of a number of miRNAs, including the down-regulation of mir-1 and mir-133a, and up-regulation of mir-21, which are usually dysregulated in cardiac hypertrophy and congestive heart failure [3,13-16].