The invention relates to an MDR family P-glycoprotein located on human chromosome 7p15-21, polynucleotide sequences encoding this P-glycoprotein and fragments thereof. This gene is utilized in methods for assessing cancer cell susceptibility to therapies directed against multidrug resistance, and for the design of diagnostic and therapeutic methods relating to cancer multidrug resistance. The invention also relates to methods for determining whether a test compound may inhibit multidrug resistance.
