The present invention is directed generally to cell culture media useful for introducing macromolecules and compounds (e.g., nucleic acid molecules) into cells (e.g., eukaryotic cells in the presence of said media. Cells containing introduced materials can be further cultured in the media. In particular, the invention allows introduction of nucleic acid molecules (e.g., vectors) into cells (particularly eukaryotic cells) and expression of proteins encoded by the nucleic acid molecules in the cells. The invention obviates the need to change the cell culture medium each time a different procedure is performed with the cells (e.g., culturing cells vs. transfecting cells). The invention thus provides efficient and high throughput methods to transform/transfect culture and cells avoiding the need for multiple manipulations and transfers of cells during transfection and expression studies.