The ETPs are known for their cytotoxic effect on cancer cell lines, and it has been shown mechanistically that ETPs were transcriptional antagonists that block the interaction of the p300/CBP coactivator with the hypoxia-inducible transcription factor HIF-1α by a zinc ejection mechanism, which resulted in rapid down regulation of hypoxia-inducible genes critical for cancer progression [208]. This evidence concerns the gene HIF1A and cancer.