Zearalenone (ZEA) and aflatoxin B1 (AFB1) are secondary metabolites produced by the fungi Fusarium and Aspergillus respectively. ZEA is proven to be an estrogenic endocrine disruptor since 1950s, while AFB1 is recently found to disrupt steroidogenesis in placenta. Both mycotoxins are constant contaminants of cereals worldwide and can both be found at significant levels in human plasma/urine of people in developing countries. Due to the co-occurrence of ZEA and AFB1 in food and human samples and the possibility of endocrine disruptors to modulate the growth of hormonal dependent breast cancer, we hypothesized that exposure to ZEA and AFB1 would affect the growth and cell cycle progression of breast cancer cells by modulating gene expressions and disrupting steroidogenesis and hormone …postprin