Figure 2.

Mutational analyses of the exon 3 region of the β-catenin gene in human osteosarcoma. Genomic DNA was purified from the tumor regions of paraffin-embedded sections of the selected samples. Exon 3 of the β-catenin gene was amplified by PCR and sequenced using the USB ThermoSequenase kit (see Material and Methods). Representative DNA sequences from 5 samples are shown. Tumor samples derived from patients 1, 3 and 4 exhibited significant cytoplasmic accumulation of β-catenin protein; the tumor sample from patient 2 was notable for marked nuclear accumulation of this protein, whereas the tumor sample from patient 3 exhibited strong nuclear and cytoplasmic staining of the β-catenin protein. Except for the specimen from patient 4 (from pulmonary metastatic tumors), all other samples were primary tumors. The frequently mutated GSK3β phosphorylation sites within exon 3 reported in other types of human cancer are indicated.