I do MTT assay to see the cell viability upon drug treatments.we have sigma plot.10 software programme.could anyone tell how to calculate IC-50 using that.
Not the answer to your question but a workaround for calculation the IC50 using Excel2007 can be found here: http://www.scribd.com/doc/9473396/Excel-2007-for-Scientists
You should verify your data before publishing but for going on in lab work it's sufficient.
Sigma plot can also be useful for IC50 calculations. though it is little tough but gives good analysis options. Go this site: http://www.sigmaplot.com/products/sigmaplot/productuses/prod-uses43.php
Comparatively Graphpad prism is much easier in EC50/IC50 calculation. If you have the Graphpad prism software, I could help you in calculating the EC50. Otherwise, if possible just share your data I let you know your EC50 value