Fig. 9. (A-C) Model of the neural crest cell response to LN isoforms. (A) On LN-1, both cell-binding domains (CBD) situated at both extremities of the 1 chain interact with the 1ß1 integrin. Erk signaling activated upon binding to the E1' CBD promotes cell survival and moderate, random migration, whereas FAK signaling after binding to the E8 CBD induces cell spreading and rapid, oriented migration. Cooperation between signals elicited by E1' and E8 is believed to promote sustained cell migration. On LN-10/11 (B), there is only one CBD located in the C-terminus of the 5 chain. This CBD is recognized by the 1ß1 integrin in crest cells and, in a manner similar to the E8 CBD of LN-1, it promotes cell spreading and rapid, oriented migration, presumably also via FAK signaling. However, because Erk signaling is not activated upon binding of LN-10/11, migration is supported only transiently and no survival is promoted. Finally, on LN-5 (C), the CBD located in the C-terminus of the 3 chain is not recognized by the 1ß1 integrin but instead by the 6ß1 integrin. However, because the 6ß1 integrin is poorly active in crest cells, interaction with LN-5 is reduced and results only in limited migration. Again, because no CBD exists in the N-terminus of the 3 chain, Erk signaling is not activated, resulting in a poor cell survival.