HIF1A and neoplasm: Inhibit cell cycle progression, promote cell apoptosis, suppress tumor stem cells, induce G2/M phase cell cycle delay, downregulate homologous recombination repair protein RAD51, induce mitochondrial ROS production and activate mitochondrial apoptosis, regulate tumor microenvironment via PI3K/HIF-1 pathway to overcome hypoglycemia and hypoxia, target Rad51 and epithelial-mesenchymal transition.