So in our discussions, we discussed epinephrine signaling, insulin signaling, EGF signaling, and we also looked at the phosphonosatide cascade. So what exactly are the four factors that these four pathways actually have in common? Well, fact number one is they all use protein kinases. Fact number two is they all use secondary messenger molecules. Fact number three is or property number three is they all depend on specific interactions between proteins and other molecules to basically stimulate that process. And number four is they all have to be terminated once they are actually complete, once they carry out their specific type of physiological effect.