[Expression of individual proteins of mouse mammary gland cancer virus in tumors in mice of various strains].

Expression of the main structural proteins of mammary gland cancer virus, gp52 and p27, was studied with the immune sera to these proteins in homogenates of tumors from mice of low and high cancer lines. Protein gp52 was found only in tumors of mice-carriers of MTV-S. In a fraction of purified type A particles from the cytoplasm of mammary gland cancer no gp52 was found, but with the antiserum to p27 this fraction reacted by a line identical to that with the antigen from C2HF mouse tumor.