Table 1.

EGF family receptors and ligands.

EGFR/ErbB1/HER1	ErbB2/HER2	ErbB3/HER3	ErbB4/HER4
HB-EGF		NRG1/2	HB-EGF
EGF			NRG1/2/3/4
TGF-α			BTC
AR			EPR
BTC
EPR
ErbB/HER homo- and heterodimers activated by HB-EGF 1/1 - 1/2 - 1/3 - 1/4 - 2/4 - 3/4 - 4/4

TGF-α, transforming growth factor-α; AR, amphiregulin; BTC, betacellulin; EPR, epiregulin; NRG1/4, neuregulin-1/4.