Now, to actually see what that means, let's discuss a specific example of a specific protein kinase that exists inside our body. And this is protein kinase A or simply PKA. So what exactly is the importance? What is the functionality of protein kinase a? When does our body actually use protein kinase A? Well, in dangerous or exciting or stressful situations, recall that it's the sympathetic division of our nervous system that kicks in and initiates the flight or fight response.