The rat testis and liver or human liver microsomes were used for 11β-HSD1 assay. 11β-HSD1 activity was performed in the microsome according to a previously described method  . In brief, the assay tubes contained 25 nM substrate 11DHC (for rat) or cortisone (for human), spiked with 30,000 cpm their respective 3 H-11keto-steroid, mM NADPH and 5 mM glucose-6-phosphaare in the PBS buffer. 2 µg microsomes were added to each tube to initiate the reaction and the reaction mixture was incubated for up to 2 hrs, during which the reaction is within the linear range. The rest procedure was similar to 11β-HSD1 assay in intact cells.