Hi,

This sounds like a tricky experiment, and you're leaving a lot to chance hoping that all four vectors will get into the same cell (highly unlikely). I would suggest making stable cells with your expression vectors, and then adding the siRNAs (allow 48 hours after siRNA before analysis ). When I do co-transfections, I always use only a total of 1ug (no matter how many vectors I'm transfecting) in a 6-well plate. Compare surface areas, and adjust total DNA as necessary. I have used 5ul lipofectamine per well (again, in a 6-well plate, adjust for surface area), but I recommend Lipofectamine RNAi Max reagent for siRNA. Use a plate with larger wells if possible, I have had issues when trying to transfect into smaller wells.

Good luck,

Danielle