Hi there Yogendra, a quick search of ethanol mcf-7 on scigine reveals that small amounts such as 1 pmol/L have no effect. People have also used it as a formulation for drugs in small amounts. However, saturating the cell with ethanol will dehydrate it and this is used for staining purposes.

I think you need to give more details in your question if you want a better response. 

http://www.scigine.com/method.php?ID=24707

I am working on MCF-7 breast cancer cells for sometime now and also time to time treat them with various agents like estrogens/antiestrogens. I dissolve estrogens in ethanol and so I have to add equivalent amount of only ethanol (without drug) to the control plate. I standardized the concentration of ethanol (dehydrated) to 1% of the culture medium without any side effect in MCF-7 cells.