Figure 3.

Relation of EBV and p53 alterations, illustrated by two representative tumors (PA57 and SE8). A: Epstein-Barr virus was detected by in situ hybridization for EBER1 nuclear RNA transcripts. PA57 is negative whereas SE8 shows strong nuclear positivity in the vast majority of tumor cells. Immunohistochemistry for p53 is strongly positive in PA57 but negative in SE8. B: Electropherograms of labeled PCR products of paired tumor (T) and normal (N) DNA. Two microsatellite markers at the TP53 locus are shown (p53 Alu and TP53). Both PA57 and SE8 are informative for each marker. The individual alleles are indicated by arrows. PA57 (EBV-negative, p53-immunopositive) shows LOH at both markers. The lost alleles are marked by asterisks. SE8 (EBV-positive, p53-immunonegative) has retained both alleles in the tumor.