ABCB1 and familial pancreatic carcinoma: In conclusion, this study has found that (1) the ABCB1 2677TT and 3435TT genotypes/haplotypes are associated with lower risk of developing pancreatic cancer; (2) the mRNA expression of ABCB1 reduced in the ABCB1 2677TT and 3435TT carriers; and (3) the ABCB1 2677TT-3455TT haplotype might be linked to an increased sensitivity to gemcitabine compared to the other haplotypes.