Ham's F12 was originally developed for the serum-free clonal growth of Chinese Hamster Ovary (CHO) cells, lung cells and mouse L-cells. It is frequently used with dialysed serum, hormones, selenium and other supplements for serum-free cultures. It is the medium of choice for supporting the growth of cells of rodent origin, particularly rabbit and rat and has proved to be an excellent cloning medium for the culture of myeloma and hybrid cells.