Cells of rat rhabdomyosarcoma RA-2 selected for high metastatic potential and affinity to lung tissue were (125I)-labelled in the presence of iodogene. The spectrum of 125I-labelled cell surface antigens was investigated by SDS-PAGE. Radionuclide was incorporated by proteins (or glycoproteins) with molecular weight of 30, 36, 47, 57, 78, 90, 102, 124, 180 and 250 kDa. After incubation of cells with 0.05-0.2% triton X-100 solution all the proteins except for those with molecular weight of 47 and 57 kDa were washed off the cellular surface; metastatic potential (MP) of triton-100 treated cells was 10 times as low as that of intact cells.