ATF4 and breast cancer: Knott et al. reported that the expression level of asparagine synthetase (ASNS) in breast cancer is closely related to metastatic recurrence and that inhibition of ASNS or restriction of dietary Asn can reduce tumor metastasis.97 In non-small cell lung cancer (NSCLC), activating transcription factor 4 (ATF4) can alter amino acid uptake and increase Asn synthesis through AKT and NRF2 downstream of KRAS.