It is clear that an essential and detailed body of knowledge is now becoming available through recent investigations in the experimental animal and in humans concerning the biochemical and genetic characteristics of tumour antigens, especially tumour-specific antigens. Hopefully, through this knowledge, we shall be able to improve the diagnosis and control of cancer. To summarize the recent findings in our laboratory, proteins p82 and p86 have been isolated and apparently purified from MC-induced sarcomas and from an SV40-induced sarcoma of BALB/c mice. Each protein, where assayed, shows a specific immunogenicity for the tumour from which it was isolated. Both p82 and p86 are present on the several sarcomas we studied and have been purified using the isolation and chromatographic procedures used initially for Meth A. On the basis of information obtained to date, p82 and p86 appear to be separate entities as determined by their chromatographic patterns, molecular masses, isoelectric points, amino acid compositions and reactivities to the specific antisera raised against the purified antigens. Each appears to be a well-conserved protein. Partial amino acid sequences obtained from p82 indicate that p82 is a unique protein. The answer to whether p82 and p86 are related or unrelated molecules, however, must wait for more complete structural studies. Such studies will hopefully lead to a molecular characterization and identification of the genetic mechanisms responsible for diversity of TATA, and will determine whether TATA within a group (for example among carcinogen-induced sarcomas) represent a family of structurally related molecules with polymorphic epitopes coded for by a single locus, or unrelated molecules coded for by several loci.
