For FFPE tissues we used liver tissues of male C57BL/6 mice that were fixed by 10% formaldehyde and embed- ded in paraffin. First, we examined dependence of pro- tein extraction efficiency from FFPE mouse liver on 20 mM, 100 mM and 500 mM TRIS, respectively, in PEB. The incubation time during the heat-treatment was also varied; 0, 30, 60, 90 and 120 min. After the treat- ment, the protein extraction efficiency was evaluated by band intensities of Grp78, Ass and Ldha observed in Western blotting (Figure 1). The band intensities of pro- teins drastically increased with prolonged incubation time of the heat-treatment. Without heat-treatment, all PEBs containing various concentrations of TRIS failed to extract proteins effectively (0 min in Figure 1A). With the heat treatment for 30 min, band intensities of Grp78