The DNA binding activity of AP-1 was analyzed by band shift assay in nuclear extracts derived from fresh tongue tissue biopsies of precancer (n = 20), cancer (n = 50) and normal adjacent control tissues (n = 30) as well as in two tongue cancer cell lines (UPCI:SCC090; HPV+ve and AW13516; HPV−ve) using γ32P-labeled probe harboring AP-1 consensus sequence. The gene discussed is FOS; the disease is cancer.