INTRODUCTIONThe efficient delivery of exogenous DNA to cells for expression and function studies is an essential technique of modern cell biology. Polymer-based systems can be used to transfect cells, some of which rely on one type of molecule, whereas others contain a mixture of polymers and lipids. Reagents such as SuperFect or PolyFect use activated dendrimers, which are positively charged and resemble snowflakes in structure. One advantage of using dendrimer-based reagents is that they appear to be less sensitive than liposomal reagents to the presence of serum during transfection. Thus, they could be a better choice for cells that show greater dependence on the continual presence of serum (to avoid initiation of stress responses or induction of differentiation). This protocol describes a procedure for dendrimer-mediated transfection.