SLCO1B3 and malignant colon neoplasm: Despite high Ct-OATP1B3 mRNA expression levels in colon cancer cells, its protein expression was not detected in the soluble membrane fraction of such cells when using either anti-OATP1B3 antibodies (which was obtained from Sigma) or anti-OATP1B3 rabbit serum (which was developed in this study) (Figure 6 and Additional file 3: Figure S3).