They could show that these effects were phenocopied in zebrafish itgb1b mutants as well and propose a mechanism whereby Rap1b activity induces Itgb1b-dependent adhesion to fibronectin to mediate close association of LPM cells with the somite and ensure a sufficiently strong induction of Notch signaling to specify HE. Here, RAP1B is linked to hereditary elliptocytosis.