Hybridoma Supplement is a chemically-defined supplement for cell culture media that supports the growth of hybridoma cells. It contains insulin, ethanolamine, hydrocortisone, retinoic acid, linoleic acid, and other growth-promoting factors. As an additive to culture medium, Hybridoma Supplement supports the growth of hybridoma in a manner feeder cells have been used before. The disadvantages occurring by the use of feeder cells may include overgrowth of newly formed hybridomas, source of contamination, competition for nutrients, and variations in growth factor concentrations. Hybridoma Supplement can be used in culture medium under serum-free conditions. The low-protein content facilitates the isolation and purification of produced antibodies. Hybridoma Supplement is provided as a 10x concentrate.