GFPT1 and neoplasm: The MS data show that the UDP‐GlcNAc level is considerably higher in the Tu‐ECs of OEGF mice than in WT mice, with the highest fold change, implying that the high expression level of GFAT1 in the tumor cells prominently promotes the HBP flux in the ECs (Figure 7H,I and Figure S6A, Supporting Information).