In order to investigate effects of cell protein phosphorylation on scavenger receptor, human U937 macrophage-like cells were treated with protein kinase C inhibitor staurosporine, then the cells were incubated with (125)I ox-LDL or ox-LDL, and the cellular degradation of (125)I ox-LDL, its binding to receptor and the internalization of cell surface ox-LDL receptor complex as well as the accumulation of lipids within cells were measured separately. Moreover, the effects of the drug on expression of cell surface receptor were observed by means of autoradiography. The results indicated that staurosporine could enhance U937 cells to bind lipids and stimulate scavenger receptor expression, and could reduce degradation of lipids by U937 cells and the accumulation of cholesterol within the cells. It suggests that the function of scavenger receptors may be correlated with cell protein phorsphorylation.