Our previous reports have shown that two thirds of 4-nitroquinoline-1-oxide (4NQO)-induced murine oral squamous cell carcinomas (SCC) have Hras1 mutations.
Exons 1-3 of the p16/CDKN2 gene, exons 4-9 of the p53 gene and exons 1 and 2 of H-, K- and N-ras genes were screened for mutations by a combination of immunohistochemistry and single-strand conformational polymorphism (SSCP) analyses of polymerase chain reaction products from human surgical samples of both frank oral squamous cell carcinomas and premalignant lesions.