FKBP1B and cardiac arrhythmia: All of these, in addition to heart failure and arrhythmia, have been suggested to originate, at least in part, through RyR2 phosphorylation and a decrease in its affinity for the immunophilin FKBP12.6 (calstabin 2) (Kushnir et al., 2018; Marx et al., 2000).