GFPT1 and breast cancer: Oikari et al. also described the up-regulation of glutamine:fructose-6-phosphate amidotransferase (GFAT), a rate-limiting enzyme of the HBP, in human breast cancer biopsies13, whereby elevated GFAT expression was in parallel with an increase in UDP-GlcNAc content and was strongly correlated with tumor hyaluronan (HA) levels.