2 day SRB – repeats very different. Further repeats required.

2 day SRB – repeats very different. Further repeats required. 2 day MTT – shows compounds to be more active

2 day SRB – % inhibition to compare to NCI data

2 day vs 7d SRB – MTT shows compounds as more active at 2 day - Much less “growth” shown by MTT (2d) SRB “growth” MTT-

Absorbance – Are the optical densities in SRB and MTT assays within the linear range of detection by our plate reader? Plates read at 550nm for both MTT and SRB assays. In assay SRB added to a final concentration of 0.08% w/v and MTT at 400 mg/ml These concentrations were used as a starting point to serially dilute SRB or MTT formazan (product of MTT metabolism by cells) in final volume of 100 ml 10 mM Tris-HCl (pH 10.0) or 150 ml DMSO respectively and absorbance at 550 nm read on plate reader. Highest 550nm absorbance for MTT = 1.759 (red line) – in linear range Highest 550nm absorbance for SRB = 2.3 (black line) – Too high? Highest 492nm absorbance for SRB = 0.528 (green line) – perhaps read at 492

2 day SRB – repeats very different. Further repeats required.