EPO-dependent expression of Nix and Bcl-xL. Cells were cultured in EPO on days 0 to 7 and then were grown in the presence (+) or absence (-)of EPO from days 7 to 14. (A) On days 9 and 14, Western blot analyses were performed on total cell lysates probed for Nix (top), Bcl-xL (middle), or GAPDH (lower) expression. K562 cell lysates (far right) are included for comparison. (B) Matching flow cytometric analyses of Annexin V staining of the cells. The percentage of apoptotic cells (brightly stained with Annexin V) is provided in the upper right corner of each panel.