HIF1A and colorectal cancer: Subsequently, atomic PKM2 functions as a coactivator of HIF-1α to promote HIF-1α-dependent expression of glycolytic enzymes, such as GLUT1, HK2, PKM2, LDHA, and PDK1, which in turn promotes aerobic glycolysis and the expression of iNOS, COX2, and NOX2, as well as the secretion of nitric oxide (NO) and reactive oxygen species (ROS), promoting the immunosuppressive function of MDSCs and thereby promoting the occurrence of colorectal cancer.