PGP and gastric cancer: In a words, 5-FU resistant GC cell lines, SGC7901/FU and MGC803/FU, were established by exposure to 5-FU for a long term, and the proliferative potentail of the 5-FU resistant cells was proved to be decreased, The drug related proteins, such as, MDR1 and P-gp were up-regulated in the resistant GC cells lines contrast with its parental cells.