CMRL media are based on the composition of Medium 199. Nucleic acid derivatives, coenzymes omitted in H597 modification were retained in CMRL 1066. CMRL 1066 is a chemically defined medium formulated for long term cultivation of mouse L cells in the absence of protein supplement. Although originally designed for use in serum free conditions, this medium supports growth of a variety of cell lines in the presence of serum. AT110 is CMRL 1066 Medium with L-glutamine. Users are advised to review the literature for recommendations regarding medium supplementation and physiological growth requirements specific for different cell lines.