Table 2.

Commonly used cardiomyocyte markers and extracardiac tissues/cell types in which they can also be expressed.

Marker	Extracardiac site(s) of expression
Nkx2.5	Embryo: Pharyngeal endoderm, spleen, stomach, tongue110, 111
GATA4	Adult: Ovary, testis, lung, liver, and small intestine112 Embryo: Proximal anddistal gut, testis, ovary, liver, visceral endoderm, and parietalendoderm112, 113
T-box 5 (Tbx5)	Embryo: Eye, forelimb, genital papilla, lung, mandible, trachea114
Myocyte enhancer factor 2C (MEF2c)	Adult: Skeletal muscle, brain, lymphocytes115, 116 Embryo: Skeletal muscle, smooth muscle, brain117, 118
Connexin-43	Ovary, testis, smooth muscle, eye, brain, macrophages, fibroblasts119, 120
Sarcomeric myosin heavy chain	Skeletal muscle121
Sarcomeric actin	Skeletal muscle122
Sarcomeric actinin	Skeletal muscle123
Cardiac troponin I	Fetal skeletal muscle124
Cardiac troponin T	Fetal skeletal muscle125
Atrial natriuretic peptide	Brain126
Smooth muscle α-actin	Smooth muscle, myofibroblasts127
Desmin	Smooth muscle, skeletal muscle128