However, in terms of cancer cells such as HepG2 cells that are widely used to study the anti-hepatoma effects of berberine [15], the expression of uptake transporters [for example, OCT1 and OATP1B3 (i.e. OATP8)] is minimal but efflux transporter (for example, P-gp) is very high [16]. This evidence concerns the gene SLCO1B3 and cancer.