MXC (99% pure) was purchased from Chemservice (West Chester, PA) in a powdered form. Stock solutions were prepared by mixing the appropriate amount of MXC with a constant volume of sesame oil. For the 8 mg/kg dose, 50 mg of MXC was mixed with 10 ml sesame oil; for the 16 mg/kg dose, 100 mg MXC was mixed with 10 ml sesame oil; for the 32 mg/kg dose, 200 mg MXC was mixed with 10 ml sesame oil; for the 64 mg/kg dose, 400 mg MXC was mixed with 10 ml sesame oil. Thus, the amount of chemical was concentrated with each subsequent dose so that mice received comparable injections based on their weights. This eliminated the need to give a greater volume injection to mice receiving higher doses than those receiving lower doses.
Cycling female CD-1 mice between the ages of 32 and 36 days were obtained from Charles River Laboratories (Wilmington, MA) and housed five animals per cage at the University of Maryland School of Medicine Central Animal Facility. In addition, our laboratory currently maintains breeding colonies of Bcl-2 overexpressing mice and Bax-deficient, or Bax knockout (BaxKO), mice. The Bcl-2 overexpressing mice were developed by Flaws et al. and are in a FVB background, and the Bax deficient mice were generated by Knudson et al. and are in a C57BL/6 background.