Figure 7.

Hif1α down-regulates Id1 and c-Myc. A) Western blot analysis of HIF1α, Id1, and c-Myc in hypoxic and normoxic conditions. B) Western blots display the expression of oxygen-insensitive HIF1α detected by Myc-tag antibody, Id1, and c-Myc in control and Hif1α-overexpressed HepG2 cells. C) Western blots show Mxi1, Id1, and c-Myc proteins in control and Mxi1-overexpressed HepG2 cells. β-Actin was used as loading control. D) According to our proposed model, the MAPK/ERK pathway functions upstream to Id1 and c-Myc. Once induced, Id1 and c-Myc positively regulate each other’s expression in a positive feedback-loop mechanism to promote aerobic glycolysis in HCC cells. Under hypoxic conditions, Hif1α suppresses both Id1 and c-Myc by recruiting Mxi1, thereby controlling anaerobic glycolysis.