Protein crumbs homolog 2 (Crb2)

Apical polarity protein that plays a central role during the epithelial-to-mesenchymal transition (EMT) in gastrulation, when newly specified mesodermal cells move inside the embryo (PubMed:26496195, PubMed:27870829). Acts by promoting cell ingression, the process by which cells leave the epithelial epiblast and move inside the embryo to form a new tissue layer (PubMed:27870829).

The anisotropic distribution of CRB2 and MYH10/myosin-IIB at cell edges specify which cells will ingress: cells with high apical CRB2 are probably extruded from the epiblast by neighboring cells with elevated levels of apical MYH10/myosin-IIB (PubMed:27870829). Also required for maintenance of the apical polarity complex during development of the cortex.