T antigen expression in FAHNSCC.

Formalin-fixed paraffin embedded tissue sections from FAHNSCC samples were immunostained with (A) P-PIT antibody-cocktail comprised of PAb416, xt7, or 2t2 or with (B) CM2B4. Black arrows indicate weak nuclear signal detected in the tumor area of these tissues. (C) Left, IHC-staining with CM2B4 of MCV positive (MCV(+) MCC) and negative (MCV(-) MCC) control tissues. Right, IHC-staining with CM2B4 of FAHNSCC-6 and FASCC-10 cases as representative examples for inconclusive (+/-) and negative (-) staining pattern respectively. (D) Detection of MCV genome with quantitative PCR in various FASCC tumor tissues and cell lines. Standard RNaseP copy number was divided by two to determine the cellular equivalent of DNA. FAHNSCC-1* DNA was extracted from the cell line corresponding to the tissue analyzed in Fig 1A and Table 1.