Based on our observations in this project, PZH may play a direct role in the degradation of HIF-1α and subsequent VEGF signaling in colorectal cancer cells and endothelial cells, leading to the inhibition of hypoxia-induced tumor angiogenesis, which is consistent with our previous study that PZH displays antitumor angiogenesis activity in the colorectal cancer mouse xenograft model [31]. Here, HIF1A is linked to colorectal cancer.