Table 1.

Nrg-1 and Nrg-2 isoform expression

Gene	Isoform	Alias(es)	Receptor(s)	Prenatal tissue expression	Post-natal tissue expression	Disease overexpression	Cell types expressing
NRG-1	Nrg1 (Type unspecified)		ErbB426 ErbB327	Lung28,29	Cornea30, skin31, skeletal muscle32,33, motor trigeminal nucleus2, breast34	Gut35	Pulmonary epithelial cells36, fibroblasts31, Golgi-II cells2, cholinergic cells of basal forebrain2
	Nrg1 Type I	Acetylcholine receptor-inducing activity (ARIA)37; neu-differentiation factor (NDF)38; heregulin (HRG)39		Hindbrain15, eye15, dorsal spinal cord15, cartilage in branchial arches15, endocardium15, trigeminal ganglion15, telencephalon15, superior/inferior colliculus15, adrenal cortex11, cortical neuroepithelium lining the lateral ventricles of the brain11, brain above the developing thalamus11, intestines11, stomach11, dorsal ganglia11, genital ridge11, liver11, dermis11	Coronary microvasculature23		Neurons40, astrocytes40, cardiac microvascular endothelial cells23,41
	Nrg1 Type II	Glial growth factor II (GGF2)10		Spinal cord15, dorsal root ganglia15, skeletal muscle15, entire brain15			Neurons40 Astrocytes40
	Nrg1 Type III	Sensory and motor neuron-derived factor (SMDF)42		Cranial ganglia,15 dorsal root ganglia,15 ventral column of spinal cord,15entire brain,15 olfactory epithelium15			Neurons43, astrocytes43, motor neurons15
	Nrg1 Type IV			Brain44	Hippocampus44, prefrontal cortex44
	Nrg1 Type V
	Nrg1 Type VI
NRG-2	Nrg2	Divergent of neuregulin-1 (DON1)45; neural- and thymus-derived activator for ErbB kinases (NTAK)46	ErbB42 ErbB32	Telencephalon46, brain45, lung45, endocardium2	Brain2,46, olfactory bulb2,46, cerebellum2,46, thymus46, brain45, lung45, cerebellum45, denate gyrus of hippocampus45, cerebellum45, liver2, spinal cord2, hippocampus2		Neurons46, granule cells45, Purkinje cells2,45, granule cells2

Tissue and cellular expression of Nrg1 and Nrg2 isoforms. Corresponding references are indicated in superscript.