Fig. 4.

Variability of OCT1 expression and correlation between OCT1 and HNF1 expression in the human liver. (A) Histogram illustrating the variability in OCT1 expression in 40 human liver samples. (B) Correlation between OCT1 and HNF1A expression in the human liver, based on analysis of 40 samples. The calculated coefficient of determination (r²) and the significance of the correlation (P) are shown. The inset represents the analyses of the subgroup of adult liver tissue donors only (age 19 years or above, n = 30). (C) Multiple linear regression analyses showing the dependence of OCT1 expression on HNF1A expression after adjustment for sex, relevant OCT1 genotypes, and HNF4 expression. Number of active OCT1 alleles is a compound genotype accounting for the loss-of-function amino acid substitutions Arg61Cys (rs12208357), Cys88Arg (rs55918055), Gly401Ser (rs34130495), Gly465Arg (rs34130495), and a deletion of Met420 (rs72552763). We regarded OCT1 alleles carrying any of these polymorphisms as inactive.