THE EFFECT OF PMA-INDUCED DIFFERENTIATION ON THE SURFACE EXPRESSION OF INTEGRINS ON CHRF-288-11 MEGAKARYOBLASTIC CELLS IN CULTURE

The integrins GPIIb-IIIa and alpha(v) beta(3) and the integrin subunit s alpha(2), alpha(5) and beta(1) have been shown by flow cytometry to be present on the surface of CHRF 288-11 megakaryoblastic cells grown in culture. PMA-induced differentiation of these cells caused a rapid increase in the surface expression of alpha(v) beta(3), the vitronecti n receptor, and a delayed decrease in surface expression of the alpha( 5) subunit (presumably present as the alpha(5) beta(1) integrin of the fibronectin receptor). PMA caused no change in expression of GPIIb-II Ia, the alpha(2) subunit (presumably present as alpha(2) beta(1)) or o f the beta(1) subunit overall. GPIIb-IIIa appeared to be present as an inactive complex on these cells.