Immunocytostaining of myeloid leukemia cells with PP-ERK-1/2 and PP-MEK-1/2 antibodies.

Cytospins of myeloid leukemia cells were stained with antibodies specific for ERK-2, PP-ERK-1/2, MEK-1, and PP-MEK-1/2 as described in “Materials and methods.” Approximately 1% to 5% of the cells were strongly stained with anti–PP-ERK-1/2 and anti–PP-MEK-1/2 antibodies. Note the nuclear staining of some cells, whereas others are stained mainly in the cytoplasm.