estrogen and MCF-7 proliferation assay - (Oct/17/2004 )

Im doing a cell proliferation assay using MCF-7 cells and estradiol. I've already done 2, which worked pretty darn well , but they used 1nM of E2. now, i have to use the amount of E2 that produces the most cell proliferation.... my supervisor suggested 100nM.... but i've seen a paper that said an amount that high might cause cell death. i can't quote that paper because it uses other drugs involved in that assay. i'm under the impression, that the max rate is achieved at 10nM... but i don't know where this is written.
can someone please tell me if this is the right amount.... and where i can get the reference from?

thanks heaps
vetticus

why not try both concentrations ?

THANKYOU!!!!
i'm actually going to do a dose dependent study on estrogen. using several concentrations, 5,10, 15 etc. probably up to 50.
thanks for the idea.