ENHANCED EXPRESSION OF CATALYTIC SUBUNITS OF PROTEIN PHOSPHATASE TYPE-1 AND HIGH S-PHASE FRACTION IN LIPOSARCOMA

The expression of the three catalytic subunits of protein phosphatase (PP) type 1 and 2A, PP1 alpha, PP1 gamma 1, and PP2AC, was examined in 8 cases of lipoma as a benign tumor and 4 cases of liposarcoma as a m alignant tumor using immunohistochemical analysis. Both types of of tu mor cells stained positively with antisera against PP1 catalytic subun it isoforms PP1 alpha and PP1 gamma 1 were significantly higher in lip osarcoma than in lipoma. Furthermore, liposarcoma showed a markedly hi gh S-phase fraction in the cell cycle of tumor cells, as compared with lipoma. These results suggest that PP1 is involved in the accelerated growth of malignant cells in liposarcoma.