kk h mk h and km h cell lines to similar final levels similar results were obtained in k562 i s9 cells expressing human pgp fig9 a through 9e and a comparison of uic2 fig1 a and mrk16 fig1 b binding of kk l cells expressing the wildtype human pgp is shown in fig1 a and 10b thus these results support the conclusion that atp depleting agents have the same effect on uic2 mab reactivity as mutagenesis of both nucleotide binding sites of pgp hematopoietic stem cells were isolated from bone marrow and umbilical cord blood using the methods of the invention fig1 bone marrow and 12 cord blood show the results of 3 color flow cytometry by facs vantage bdis analysis of human bone marrow and umbilical cord blood samples the cells were stained with 1 pe conjugated uic2 2 fitc conjugated anti cd38 mab and 3 allophycocyanin apc conjugated anti cd34 mab in the presence or absence of vinblastine the enhanced up to 10 fold binding of uic2 mab to bone marrow and cord blood stem cells was observed in the presence of vinblastine proving that the described phenomenon can be used for improved labeling of stem cells with ulc2 and their consequent purification by conventional separation techniques it should be understood that the foregoing disclosure emphasizes certain specific embodiments of the invention and that all modifications or alternatives equivalent thereto are within the spirit and scope of the invention as set forth in the appended claims __________________________________________________________________________ sequence listing 1 general information iii number of sequences 2 2 information for seq id no 1 i sequence characteristics a length 4669.