The mouse DAO transiently transfected CHO-K1 cells were trypsinised, resuspended in complete medium and centrifuged at 1200 rpm for 4 minutes at room temperature. The cell pellet was then washed in 10mM HEPES buffer and centrifuged at 1200 rpm for 4 minutes at room temperature. The resulting cell pellet was resuspended in 10 mM HEPES buffer at 1.75x10 6 cells/mL.