Zearalenone is 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 ER?? and ER?? respectively) and was found to stimulate the transcriptional activity of both subtypes at concentrations between 1 – 10 nM.