1. Neuregulins and Their Receptors: A Versatile Signaling Module in Organogenesis and Oncogenesis 
Steve Burden, Yosef Yarden 
Neuron 
Volume 18, Issue 6, Pages (June 1997)
DOI: /S (00)

2. Figure 1 Physiological Functions of the NRG-ErbB Signaling Module
The center panel schematically shows the four ErbB proteins crossing the plasma membrane (horizontal bar). ErbB-3 and ErbB-4 are the direct NRG receptors, whereas ErbB-1 and ErbB-2 function as coreceptors. The tyrosine kinase domain of ErbB-3 is inactive (crossed). The color code of the receptors is maintained in the other panels, each presenting one of the known roles of NRGs (functions symbolized by thick arrows). Note juxtaposition of the sources of NRG (blue) and the responsive cells (red). AChR, acetylcholine receptor; SC, Schwann cell; and NRG, neuregulin.
Neuron  , DOI: ( /S (00) )