TwoDimensional Electrophoresis of Membrane Proteins from Normal and Transformed Cell&

have been previously reported (27). We have found that many of the immunogenic viral and spontaneous transformants have a number of characteristic alterations in cell membrane com ponents as described by Strand and August (25). In contrast, a malignant spontaneous transformant does not have these changes and appears to be very similar to the normal cells. In addition, all of the transformants showed changes in the isoe lectnic points of glycoproteins relative to the normal cell line. Sialic acid content alone could not account for the differences. It is possible that intracellular alterations and/or modifications of these membrane glycoproteins may contribute to the expres sion of a transformed phenotype in vivo.