In adult mice, axotomy of facial motoneurons induces apoptotic cell death. Cpp32, Bax and Bcl-xl are regulators of this type of cell death in the central nervous system. Using in situ hybridization, we have studied the kinetics of expression of cpp32, bax and bcl-xl mRNAs after a fatal lesion of the facial nerve in wild-type and Bcl-2 transgenic mice, where cell death is known to be prevented. In both strains of mice, cpp32 mRNA was up-regulated by 12 h following axotomy whereas changes in bax mRNA expression occurred later (from 3 days). These results provide information on the timing of molecular processes involved in cell death and could be helpful in determining a critical period during which they may be blocked.