ABCB1 and gastrointestinal stromal tumor: A total of 68 Chinese GIST patients who have received IM 300–600 mg/day were genotyped for six single nucleotide polymorphisms (SNPs) (CYP3A4 rs2242480; ABCB1 rs1045642; ABCG2 rs2231137; NRI12 rs3814055, rs6785049, rs2276706), and the steady-state IM trough plasma concentrations were measured by a validated HPLC method.