Plate growing cells at 50–60% confluency for 12–18 h before transfection. Transfect cells with the plasmid encoding the gene of interest (or siRNA) along with a marker plasmid (i.e., GFP) in a 7:1 ratio, or with a vector-encoding GFP fusion protein containing the gene of interest by LipofectAmine and PLUS transfection reagents (Invitrogen). Incubate the dishes at 37 °C until cells reach 100% confluence to form a monolayer.