Figure 4.

β-Catenin and ABCB1 expression in human colon carcinomas. (A) Thirty three primary colon carcinomas from untreated patients were analysed for β-catenin Δ45 mutation by RT–PCR-based restriction fragment length polymorphism (Stein et al, 2006). We identified three tumours to be heterozygous for the β-catenin Δ45 mutation. The mut β-catenin RT–PCR product is cut by Bsl I (fragments 72 and 48 bp), whereas the wt β-catenin RT–PCR product (123 bp) is not. (B) The nuclear localisation of β-catenin is clearly seen in these three tumours, together with high expression levels of ABCB1 protein. Subcellular localisation of β-catenin as well as ABCB1 protein expression was determined by immunohistochemistry in consecutive sections of these heterozygous tumours. Sections without primary antibodies served as controls; bars, 20 μm.