1-4-1. Regulation of cancer cell metabolism by thePKB; The PKB (Protein kinase B/Akt) signaling pathwayhas been shown to promote continued cell growth and coordinatesthe necessary metabolic changes to support cellgrowth by increasing glucose uptake, glycolysis and ATPproduction. Activation of PKB signaling may be a factorleading to the switch to glycolytic metabolism in cancer (52)(Fig. 1). PKB directly and/or indirectly regulates the transcription(60) and translation (61) of GLUT1, which functionsin glucose uptake. PKB also activates hexokinase 2(HK2) association with the mitochondria, promoting thephosphorylation of glucose to glucose 6-phosphate, to bemetabolized via glycolysis or the pentose phosphate pathway,and the mitochondria-associated HK2 is involved inthe inhibition of apoptosis (62,63). Moreover, PKB regulatesde novo fatty acid synthesis and the usage of fatty acidfor β-oxidation. It phosphorylates ATP citratelyase (ACL),stimulating the cleavage of citrate to oxaloacetate and acetyl-coenzyme A (Ac-CoA) to supply downstream de novofatty acid synthesis (64). Phosphoinositide 3-kinase (PI3K)and PKB suppress the expression of the β-oxidation enzymecarnitine palmitoyltransferase 1A (CPT1A), and the modulationof CPT1A expression by PI3K/PKB signaling is themechanism to suppress β-oxidation during cell growth (65).The mammalian target of rapamycin (mTOR), a downstreameffector of the PI3K/PKB pathway, is situated at thecrossroads of signaling pathways and is an integration centerfor signals bringing the coordinated regulation of nutrientuptake, energy metabolism, cell growth, proliferation,and cell survival (66,67). mTOR is regulated by AMP-activatedprotein kinase (AMPK) (the cellular energy sensor),tuberous sclerosis 1 & 2 (TSC1-TSC2) complex, and Rashomolog enriched in brain (RHEB) (68). Most importantly,mTOR is an upstream activator of HIF-1α in cancer cells(69), which is a subunit of a transcription factor that upregulatesthe expression of nearly all of the genes involved in