I have been trying to study the dose-response curve of paclitaxel (purchased from Santa Cruz) on pancreatic cancer cell lines (panc1, ASPC1, CFPAC-1)... I use drug concentrations starting from 0.01 nM to 10uM ... Though my drug range is wide enough, my cells weren't responding well, and my dose response curve remains more like a straight line.. Has anyone experienced like this? Could you guys please help me?