AT290 is Nutrient Mixture F-12 Ham with 10mM HEPES and L-glutamine. This medium supports growth of cells of rodent origin. It also allows cloning of myeloma and hybridoma cells and it is medium of choice for clonal toxicity assay using CHO cells. Ham's Nutrient Mixture F12 was originally designed for serial propagation and cloning of two CHO cell lines namely, CHD-3 and CHL-1 and mouse L cells. It is the medium of choice for the growth of cells of rodent origin and for cloning of myeloma and hybridoma cells. This medium is also the medium of choice for clonal toxicity assay using CHO cells.