Total cellular expression of OCT2 in human kidney cortex and OCT2-expressing HEK293 and MDCKII cells and plasma membrane expression of OCT2 in OCT2-expressing HEK293 and MDCKII cells. (A) OCT2 expression in the human kidney cortex (n = 5), HEK293, and MDCKII cells was 7.6 ± 3.9, 369.4 ± 26.8, and 19 ± 1.1 pmol/mg protein (mean ± S.D. of triplicates of a single experiment). (B) The percent of total OCT2, Na+-K+-ATPase and calreticulin expressed in the plasma membrane of OCT2-expressing HEK293 (mean ± S.D, n = 3 independent experiments) was 30.2 ± 1.9, 58.8 ± 3.6, and 6.7 ± 2.3, respectively, while that in MDCKII (average of n = 2 independent experiments) was 51.6, 83.7, and 11.1 respectively. Mass balance showed that the recovery of all proteins was 94.5%–114.4%. Data are average of two and three independent experiments for OCT2-expressing MDCKII and HEK293 cells, respectively.