Zearalenone, a phytoestrogenic mycotoxin usually produced by Fusarium species, is shown to be a cytotoxic compound, but alos binds to the estrogen receptor (ER) (IC50 values are 166 and 240 nM for ERβ and ERα respectively) and was found to stimulate the transcriptional activity of both subtypes at concentrations between 1 - 10 nM. This agent has demonstrated the ability to induce apoptosis via activation of mitochondrial release of Cytochrome c, production of reactive oxygen species (ROS), activation of caspase-3 and caspase-8, and induction of endoplasmic reticulum stress. Additional studies sμggest that Zearalenone also up-regulates Bax expression and down-regulates Bcl-xL expression in cells, which also contribute to a halt in cell proliferation. The cell growth arrests caused by this mycotoxin seem to take place during the G1 phase of the cell cycle.A phytoestrogenic mycotoxin and ER activator Zearalenone, a phytoestrogenic mycotoxin usually produced by Fusarium species, is shown to be a cytotoxic compound, but alos binds to the estrogen receptor (ER) (IC50 values are 166 and 240 nM for ERβ and ERα respectively) and was found to stimulate the transcriptional activity of both subtypes at concentrations between 1 - 10 nM. This agent has demonstrated the ability to induce apoptosis via activation of mitochondrial release of Cytochrome c, production of reactive oxygen species (ROS), activation of caspase-3 and caspase-8, and induction of endoplasmic reticulum stress. Additional studies suggest that Zearalenone also up-regulates Bax expression and down-regulates Bcl-xL expression in cells, which also contribute to a halt in cell proliferation. The cell growth arrests caused by this mycotoxin seem to take place during the G1 phase of the cell cycle. A phytoestrogenic mycotoxin and ER activator