[Oncoprotein p21-ras expression in epidermoid carcinoma of the laryngopharynx].

Ras genes can acquire transforming properties by qualitative and quantitative mechanisms. The mutated products of ras oncogenes (p21 protein) exhibit a decreased ability to hydrolyze GTP that lead to the stabilization of ras proteins in their active state and cause a continuous flow of signal transduction which may result in malignant transformation. These biochemical aberrant properties can also be achieved by an increased expression of the normal p21 protein. In this work we have analyzed the presence of ras gene mutations and the overexpression of the oncogene product p21 in the same series of squamous cell carcinoma of pharynx and larynx. Of 13 cases studied we have detected mutations in seven cases and in nine we have observed overexpression of the p21 protein. There is no correlation between ras mutations and overexpression of the p21 protein.