FACScan analysis of parental CMK cells treated with PMA or transfected with vector, WT Mek, DE Mek or D330N Erk. CMK cells were analyzed by FACScan as described. Cells were gated to exclude nonviable cells using propidium iodine staining. (⋅⋅⋅⋅⋅⋅) Represents the isotype control, (– – –) denotes the staining with markers of megakaryocytic differentiation, CD41 or CD61. (A) CD41; (B) CD61.