STK11 and atrial fibrillation: Additionally, AMPK activation by CB13 is likely not mediated through LKB1 activation (Figure 5B) and is therefore likely achieved through changes in cellular Ca2+ levels, particularly since Ca2+/calmodulin-dependent protein kinase kinases (CAMKKs) and reactive oxygen species (ROS), which promote AF, have been implicated to alter AMPK signalling (Lin et al., 2004; Kim et al., 2016).