About RNAi based on sh-RNA plasmid - (Aug/23/2005 )

I am doing something about RNAi. I used a plasmid encoding RNAi fragement which was successfully used by other people,for target sequence of GFP. For transfection, I used lipofectamin 2000. 24 hours after transfection, I analysis the expression level of GFP,but none change was observed. I am confused! What shoud I do next? Hope anyone`s help!

Have you tried 48-72 hrs transfection? There are variables affecting transfection efficiency such as cell density at transfection, concentration of siRNA, lengh of transfection, etc. Is the shRNA plasmid constructed by yourself and if so have you verified the sequence of the plasmid?

thank you for your reply!