Activation of ERK-1/2 and MEK-1/2 in myeloid leukemia cell lines.

Myeloid leukemia cell lysates were adjusted for protein concentration and equal amounts of total cell protein were subjected to SDS-PAGE. Western analysis was performed with antibodies against MEK-1, ERK-2, PP-MEK-1/2, and PP-ERK-1/2. L61-H-RAS–transformed NIH-3T3 cell lysates were used as positive controls for the RAS-induced activation of ERKs and MEKs.