FOXP3 and neoplasm: We then performed single-cell RNA sequencing (scRNA-seq) to profile intratumoral CD45+ immune cells—which included CD8+ T cells, FOXP3–CD4+ T cells, FOXP3+CD4+ T regulatory (Treg) cells, cDC1s, cDC2s and plasmacytoid DCs (pDCs) (Extended Data Fig. 1h)—and CD45– non-immune (predominantly tumour) cells from PBS or glutamine-treated MC38 tumours for mechanistic insights (Methods).