HIF1A and cancer: A triterpenoid compound named cucurbitacin B isolated from Trichosanthes kirilowii showed the potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines. In vivo studies confirmed the inhibitory effect of cucurbitacin B on the expression of HIF-1α proteins, leading to a decrease growth of HeLa cells in a xenograft tumor model [77].