Fig. 5. Cell surface expression of differentiation marker CD41. Wild-type K562 cells and the mutant clones were treated with DMSO or PMA for 6 days before collection. Cells were stained with the control antibody ZPO-1 or with antibodies directed against CD41 and CD61. Bound antibody was detected with FITC-conjugated goat antimouse antibody. Histograms of the fluorescence intensity are reported for wild-type cells and for mutant clones C1 and C4.