rev-erbα expression is also regulated at the post-translational level: it is phosphorylated on the amino terminus by glycogen synthase kinase (gsk 3β), which contributes to its protein stability. it has been shown that lithium, which inhibits gsk3β, can de-stabilize rev-erbα protein and affect its function in the circadian clock. this may partly explain lithium’s therapeutic effect on circadian diseases such as bipolar disorder.