In the type of renal carcinoma cells producing N-GlcNAc2-modified proteins, the expression of GFPT1 (glutamine-fructose-6-phosphate aminotransferase 1), a rate-limiting enzyme belonging to the UDP-GlcNAc biosynthesis pathway, or UAP1 (UDP-N-acetylglucosamine pyrophosphorylase 1), a key enzyme belonging to the UDP-GlcNAc biosynthesis pathway, was significantly activated (i.e., 3-fold increase) 6–9 h after the start of glucose deprivation. The gene discussed is UAP1; the disease is renal carcinoma.