PGD and head and neck squamous cell carcinoma: We next identified the specific PPP genes enriched in HNSCC by performing qPCR analysis, and the results demonstrated that G6PD, 6-phosphogluconate dehydrogenase (PGD), and TKT were significantly suppressed in NRF2-knockdown HONE-1 and Ca9-22-D1 cells (Figure 5D).