- Characteristics of mutations in the p53 gene of oral squamous-cell carcinomas associated with betel-quid chewing in Sri Lanka. Chiba, I., Muthumala, M., Yamazaki, Y., Uz Zaman, A., Iizuka, T., Amemiya, A., Shibata, T., Kashiwazaki, H., Sugiura, C., Fukuda, H. Int. J. Cancer (1998)