Genomic DNAs of 14 mammary tumors were analyzed by Southern blot hybridizat
ion using a human c-yes-1 oncogene probe. The amplification was successful
in half of the cases (7 adenocarcinomas). The degree of amplification was a
pproximately 4-fold, and a high proportion was seen in malignant tumors. In
addition, DNA polymorphism was detected in two adenocarcinomas.