We recently reported that PIK3CA mutant colorectal cancers (CRCs) are addicted to glutamine through up-regulation of glutamate pyruvate transaminase 2 (GPT2). A GPT2 inhibitor suppresses in vivo growth of PIK3CA mutant, but not wild-type, CRCs. This study indicates that targeting glutamine may be an effective approach to treat CRCs with PIK3CA mutations.