GO:0003199

endocardial cushion to mesenchymal transition involved in heart valve formation

Details: 
A transition where an endocardial cushion cell loses apical/basolateral polarity, severs intercellular adhesive junctions, degrades basement membrane components and becomes a migratory mesenchymal cell that will contribute to the formation of a cardiac valve. [GOC:mtg_heart]
Evidence Code: 
IGI