To determine whether loss of ASCT2 sensitizes to a low-serine environment in vivo, we switched a cohort of ASCT2 KO and control mice to a serine- and glycine-free diet (−SG) after tumors were established, whereby we observed the expected inhibitory effect of dietary serine starvation on control MCF7 tumors.20 Critically, we found that dietary serine starvation in addition to ASCT2 KO not only inhibited tumor growth but resulted in regression of nearly all tumors (Figures 7E and 7F). Here, SLC1A5 is linked to neoplasm.