TransIT-mRNA Transfection Kit efficiently delivers both mRNA and viral RNA of various lengths to a range of cell types. In addition, transfection of mRNA leads to high level protein expression with minimal cytotoxicity. This kit has been optimized for use in the presence of serum containing media, thus eliminating the extra steps of media change or serum addition. Cell lines successfully transfected include A549, CHO-K1, COS-7, HEK 293, HeLa, HepG2, NIH 3T3 and Vero cell lines.