PRKAA1 and neoplasm: In the mTOR signaling pathway, the upstream of AMPK is regulated by LKB1 and CaMKK2, which activate AMPK under low energy metabolic stress and Ca2+ respectively, while the tumor suppressor gene FLCN inhibits activation of AMPK, phosphorylation of TSC2 (activation) and RAPTOR (inhibition) downstream of AMPK inhibit mTOR activity, which in turn reduces mRNA translation [133].