Effect of the PKC inhibitors staurosporine and calphostin C on the EPO-induced erythroid differentiation of CD34⁺cells.

CD34⁺ cells were cultured in medium alone or in the presence of EPO (5 U/mL) or EPO (5 U/mL) and SCF (50 ng/mL), with or without staurosporine (50 nmol/L or 20 nmol/L) or calphostin C (50 nmol/L or 20 nmol/L) for 7 days and then stained with the indicated monoclonal antibodies. (A) Immunophenotyping of CD34⁺ cells cultured in the presence of EPO and SCF without or with staurosporine (50 nM) or calphostin C (50 nM). A representative of 6 separate experiments is shown. GPA, glycophorin A. CD34⁺ cells with or without staurosporine or calphostin C were cultured in medium alone (B), in the presence of EPO (C), or in the presence of EPO and SCF (D). indicates the percentage of GPA⁺ cells, ▧, CD13⁺ cells, and ▩, of CD15⁺ cells. Mean ± SEM of 6 separate experiments (3 for the calphostin C results).