Abstract
An analysis of the constituents of the plasma membrane of a methylcholanthrene-induced sarcoma (the MC1 tumour) in a hooded rat revealed four tumour-associated macromolecules. Two of these were antigenic in the syngeneic host, one was unique to the MC1 tumour and could not be detected in embryo tissue and has the properties to be expected from the well established tumour-specific transplantation-type antigen while the other, referred to as OEA I, was present in all rat sarcomata tested as well as in early embryos. Two other embryonic components were detected in the sarcoma but these were not immunogenic in the rat. The properties of these tumour-associated "antigens" in the membrane of rat sarcomata are summarized below: [Table: see text]