MDR-1/Pgp is known to be overexpressed in peripheral T-cell lymphoma7, 8 in the lymphoma cells, residual lymphocytes, and endothelium,8 and this might account for the reported efficacy of the nucleoside analogue gemcitabine in peripheral T-cell lymphoma, which is not a substrate of the efflux pump.27 The gene discussed is ABCB1; the disease is lymphoma.