MTOR and juvenile Huntington disease: Ca2+-mediated inhibition of autophagy has been mostly focused on inositol 1,4,5, triphosphate (IP3) receptor (IP3R).15, 16 In Huntington's disease cell model, lithium ions have been shown to stimulate autophagy in a novel mTOR-independent manner.40 Lithium acted through inhibition of the inositol monophosphatases, thereby reducing the IP3 levels, which reduced the stimulatory effect of lithium on autophagy.