PGP and renal carcinoma: The Ex-76 T/A has been shown to be in linkage disequilibrium with G2677T and the alleles of Ex-76 T/A formed major haplotypes with G2677T and C3435T.[14] Although data to date are mainly available for coding SNPs in exons 21 and 26, Uwai et al.[13] found that Ex-76 T/A (intron 16) polymorphism resulted in downregulation of P-gp function in renal carcinoma cells.