The specificity of chromosome A2 involvement in DMBA-induced rat sarcomas

The chromosomes of 13 sarcomas induced in the rat by 7,12-dimethylbenz(α)anthracene (DMBA) were studied in direct preparations and in early cultures, using conventional and G-banding techniques. In 12 of the 13 tumors additional material of chromosome A2 was involved in the stemline karyotypes, either as complete extra chromosomes A2 or as marker chromosomes containing segments of A2. These observations strengthen the earlier conclusion that increase in the proportion of A2 material in the karyotype favors the development of DMBA tumors. Several of the markers were apparently identical to markers reported in DMBA leukemias by other workers. By detailed structural analysis of the A2-containing marker chromosomes the segment of critical significance was tentatively located to certain bands in the middle region of A2.