Proteome maps of microsomes and their ghosts (i.e. membranes purified from "ballast" proteins) were obtained using highly purified mouse liver microsomes. Comparative analysis of protein composition of ghosts without and after the induction with phenobarbital (cytochromes P450 inducer) by using 1D- and 2D-electrophoresis and MALDI-TOF-mass-spectrometry revealed more than 30 new proteins. in the course of induction in the 45-60 kDa range (corresponding to the mol. weights of cytochromes P450). In the 17 kDa range (corresponding to the mol. wt. of cytochrome b5) there were 4 additional protein stains about 20 proteins disappeared over the entire electrophoregram). Separation of microsomal ghosts proteins by 1D electrophoresis followed by mass-spectrometric analysis allowed to identify cytochromes P450. The present investigation demonstrates the efficiency of different proteomic methods combination (1D- and 2D-electrophoresis, mass-spectrometry, bioinformatics and determination of the enzyme activities) for cytochromes P450 identification and elucidation of their functioning in different animal tissues and then extrapolating this approach to humans.