Abstract
Rous sarcoma virus (RSV) mutants, which bear temperature sensitive (ts) defects in both the maintenance of cell transformation and the expression of tumour specific cell surface antigen(s) (TSSA), have yielded a number of revertants. In seven revertants studied, the acquisition of wild type transforming capacities is always accompanied by a wild type TSSA expression. This strongly indicates that transformation and TSSA expression in RSV are affected by the same mutation.