This protocol is used to dissociate adult (10 week) CD-1 mouse liver "on ice", preserving authentic gene expression profiles. The first layer consists of 3.5 hours rotation at 4 °C in 0.25% trypsin, and the second layer consists of 15 min. in bacillus licheniformis, with trituration on ice. The yield is 5000 cells/mg with 97% viability (as measured by trypan blue).