BCAT1 and neoplasm: BCAA activate the mTORC1 pathway to stimulate protein synthesis, tumor growth and survival, but can also be metabolized into branched-chain α-keto acids in a process involving conversion of α-ketoglutarate to glutamate (catalysed by BCAT1 or BCAT2 BCAA transaminase activity), and/or further catabolized to acetyl-CoA and succinyl-CoA that feed into the TCA (42).