Expression and function of FLAG-tagged hβc proteins in FDB2 cells.

(A) Flow cytometric analysis of FDB2 cells expressing FLAG-tagged hβc subunits. FDB2 cells expressing the indicated FLAG-tagged hβc subunits were stained with the anti-FLAG monoclonal antibody M2 (solid lines). As controls, uninfected FDB2 cells were stained identically (dashed lines). (B) Time course of proliferation of FDB2 cells expressing FLAG-tagged hβc proteins. FDB2 cells were washed and cultured in IL-3 (▪) or GM-CSF (▴) or in the absence of growth factors (▾), and the number of viable cells was determined periodically with the use of a hemocytometer. (C) Time course of differentiation of FDB2 cells expressing FLAG-tagged hβc proteins. In the same experiment as in B, samples of FDB1 and FDB2 cells cultured in the presence of the indicated growth factors or in the absence of growth factors (-GFs) were cytocentrifuged periodically, and the proportion of differentiated granulocytes (▪, dashed lines), the proportion of macrophages (▴, dashed lines), and the total proportion of differentiated cells (♦, solid lines) were determined from at least 200 cells scored microscopically. As shown in B, no viable cells were present in ^Fhβc -GFs beyond the second day of culture.