By means of the tumorigenicity assay applying DNA from a patient with a gastric carcinoma (MA) we have already reported the identification of the putative oncogene myeov. In addition we have shown its involvement in t(11;14)-positive multiple myelomas and amplifications of breast tumours and esophageal carcinomas. The failure of myeov cDNA to induce tumour formation in NIH/3T3 cells prompted us to analyze the human sequences present in our MA-T1a1 tertiary transfectants. Sequence analysis revealed the presence of the human oncogene hst (fgf4) at a distance of approximately 9kb from the myeov gene in our MA-T1a1 tertiary transfectants. Both myeov and hst (fgf4) are normally situated approximately 475-kb apart at band 11q13, a region that is frequently amplified and overexpressed in various tumours. Southern and Northern blot analyses confirmed our sequence data and showed rearrangement of hst sequences during the transfection process and its expression in our MA-T1a1 tertiary transfectants.