Hepatic expression of OATP1B1, OATP1B3 and OATP2B1 varies between individuals, but is coordinately regulated within one individual. (a) Representative immunoblot of liver membrane fractions (20 μg) quantified relative to a standard liver sample. (b-d) Correlation analyses of OATP protein and SLCO mRNA levels in human liver samples. (e, f) Correlation analyses of all three OATPs showed a coordinated expression of SLCO1B1, SLCO1B3, and SLCO2B1 mRNA and OATP1B1, OATP1B3, and OATP2B1 protein levels in the non-cholestatic liver sample set. rS, Spearman rank-order correlation coefficient.