AKT1 and major depressive disorder: Since miR-98-5p has previously been reported to regulate PI3K/Akt signaling pathway [28], which is significantly involved in depression [29], and the involvement of PI3K/Akt in the antidepressant effect of ketamine has also been reported [30], we speculate that ketamine-induced upregulation of miR-98-5p may elicit the antidepressant effect through regulating PI3K/Akt pathway.