CSN3 and atrial fibrillation: As both shortening and prolongation of atrial APD confer increased susceptibility to AF (Li et al., 2009; Qi et al., 2014; Zhang, Wu, et al., 2014; Zhang, Timofeyev, et al., 2014), the therapeutic efficacy of interventions targeting KCa channels will likely depend on achieving a delicate functional KCa homeostasis that is affected by individual patient characteristics and by environmental factors that determine specific KCa channel remodeling.