The alpha-MHC-mCherry transgene contains a cardiac-specific alpha myosin heavy-chain (Myh6) mouse promoter sequence upstream of an mCherry fluorescent protein cDNA sequence. The modified mouse Myh6 promoter sequence is minimally active/attenuated through the ablation of three GATA sites and two thyroid-like response elements, thereby directing cardiac-specific mCherry expression and decreased background expression. Founder line 2 were found to have extremely bright mCherry fluorescence in the heart at all stages of development. (J:188625)