It seems that concentration gradients of morphogens outside a cell ... cascade—the first step of which is the cell "seeing" the morphogen by binding to it on the surface, and the final step ...
Retinoic acid (RA) is one of several molecules that pattern vertebrate embryos by forming an anterior to posterior (A–P) concentration gradient. The issue of whether RA is a classical morphogen ...
“How these morphogens form signaling gradients in growing tissues is poorly understood,” explains Anna Kicheva. “Finding out more about them—and how morphogen production is regulated—is ...