What is FGF?

FGF is a type of receptor tyrosine kinase. What, you might ask, is a receptor tyrosine kinase? Well, since you were so kind as to ask, and since I'm a bit of a nerd at heart, I'll tell you. Receptor tyrosine kinases are a part of the machinery of a cell; they have a role in signaling to the rest of the cell what it should do.