From Jackson Labs: BALB/c mice are particularly well known for the production of plasmacytoma on injection with mineral oil, forming the basis for the production of monoclonal antibodies. Mammary tumor incidence is normally low, but infection with mammary tumor virus by fostering to MMTV+ C3H mice dramatically increases tumor number and age of onset. BALB/c mice develop other cancers later in life, including reticular neoplasm, primary lung tumors, and renal tumors. BALB/cByJ was separated from the BALB/cJ strain in 1935. BALB/cByJ mice have the advantage of better reproductive performance and less aggression than the BALB/cJ substrain. Rare spontaneous myoepitheliomas arising from myoepithelial cells of various exocrine glands have been observed in the BALB/cByJ substrain. BALB/cByJ has a deletion in the Qa2 subregion of the murine MHC. A deficiency of Acads (acyl-Coenzyme A dehydrogenase, short chain) leads to severe organic aciduria. BALB/cByJ develop a fatty liver upon fasting or dietary fat challenge and become hypoglycemic after an 18-hour fast.