Myelination in the peripheral nervous system (PNS) is induced by close contact signaling between axons and Schwann cells. Previous studies have identified membrane-bound neuregulin-1 (Nrg1) type III, expressed on the axons, as the key instructive signal that regulates Schwann cell myelination. In our recent study, we show that recombinant soluble Nrg1 elicits a similar pro-myelinating effect on...