Effects of MDR1 1236C > T-2677G > T-3435C > T polymorphisms on the intracellular accumulation of tacrolimus, cyclosporine A, sirolimus and everolimus.

1. Overexpression of P-glycoprotein (P-gp, encoded by MDR1) mediates resistance to multiple immunosuppressors. Several common MDR1 variants (1236C > T, 2677G > T, 3435C > T) impact the efflux activity of P-gp-mediated substrates.