The receptors for a group of signaling molecules known as growth factors are often Naim 01:33 AP Biology Chapter 11 The receptors for a group of signaling molecules known as growth factors are often A) ligand-gated ion channels. B) G-protein-linked receptors. C) cyclic AMP. D) receptor tyrosine kinases. E) neurotransmitters. Answer: D Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+