To small amount of cells used for shRNA transfection - (Apr/15/2013 )

Hi,

I have done a shRNA transfection but somehow the calculation went wrong and the next day of transfection there is only about 30% confluent cells, what can I do now. Is it possible to do another transfection on these cell?
My idea was that on day 3 of transfection to induce differentiation and can I still do it will the data be reliable and how long will the shRNA be there in the cells, I belive when the cells proliferate the lose it?

Thanks to everybody and I hope many people can learn from this

Depending on the cell line and target the shRNA may be there for up to 10 days, but the only way to tell is for you to do the assay yourself. 30% isn't too bad for transfection, but it may be too few cells to give you usable data at the end, though this depends on what sort of data you are gathering (FACS, protein, RNA, DNA, growth rate...)