What do you exactly mean by studying gene expression? 3D gels can be used for several different application based on the aims and requirements. The principles of RT-PCR and 3D gels are totally different and it would be good if you can read thoroughly about the method before making any plans of use. It seems like you are asking this question out of the nascent curiosity, it okey to do that. But in this case it would be hard to answer your question with any useful details.
Abhijeet Singh thank you for your reply but I want to study the whole expression of genes (i.e I want to use 3D electrophoresis instead of microarray is this possible?) Regards