MTT OD values: 490nm? 570nm? or 630nm? - (Oct/15/2009 )

I used MTT assay to get known of cell proliferation. I dont know which OO values to be used. Single-wavelength 490nm? 570nm? 630nm? Or dual-wavelength?
Please give me some advice, thanks.

Formazan, the product of MTT reduction, has an absorbance at 493nm in when solubilized in DMSO, so 490nm would be your best choice from the filters you mentioned.