Molecular cloning of feline lung resistance-related protein (LRP) was performed to evaluate the relationship between its expression level and drug resistance against chemotherapeutics. The nucleotide sequence of the coding region of feline LRP cDNA was found to be 2670-bp long and to show 84.2-92.6% homology to its human, mouse, and rat counterparts. The expression level of feline LRP mRNA was relatively high in lung, jejunum, and colon. An adriamycin (ADM)-resistant feline lymphoma subline, FT-1/ADM, showed a high level of MDR1 mRNA expression compared with parental FT-1 cells. However, no relationship was observed between the drug-resistant phenotype and the LRP mRNA expression level. Although no direct contribution of LRP to the development of the drug-resistant phenotype was observed, further investigation is advisable.