(A) RT-PCR analysis (- TST; + HCC) and Western blot analysis (B) of eleven patients with HCC and the corresponding TST. Protein expression and downregulation of the transporters, especially OCT1, correlate well compared with the RT-PCR data. Stably transfected cancer cell lines (pcDNA3_OCT1h) served as positive control for OCT1 (Pos.); (OCT1: 61kD; OCT3: 60kD). (C) Analysis of OCT1 protein expression by immunofluorescence. OCT1 shows a membranous staining in normal liver tissue, whereas the protein is downregulated in HCC (D). Tumor borders of two cases with downregulation of OCT1 in HCC (upper panel: case 2--Figure 3A/3B; lower panel: case 3--Figure 3A/3B). There is a diffuse staining near the tumor border as well as in the tumor tissue (lower panel) suggesting that the transporter function is affected in HCC.