The integrins GPIIb-IIIa and alpha(v)beta(3) and the integrin subunits 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 vitronectin 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-IIIa, the alpha(2) subunit (presumably present as alpha(2)beta(1)) or of the beta(1) subunit overall. GPIIb-IIIa appeared to be present as an inactive complex on these cells.