FIGURE 5.

Inhibition or RUNX1 cdk phosphorylation in mammalian cells increases HDAC1 interaction. A, 293T cells transiently transfected with myc-RUNX1 and FLAG-HDAC1 42 h previously were cultured in the absence or presence of a cdk inhibitor (roscovitine) for 3 h. Cell extracts were then prepared and subjected to immunoprecipitation (IP) with rabbit anti-Myc antiserum or normal rabbit Ig followed by Western blotting (WB) with mouse anti-Myc antiserum (top panel), rabbit anti-phospho-Ser-424 RUNX1 antiserum (middle panel), or mouse anti-FLAG antibody (bottom panel). Immunoprecipitated FLAG-HDAC1 was quantified as indicated below the bottom panel. B, similar analysis was conducted with cells cultured in the absence or presence of a MEK inhibitor (U0126), a PI3K inhibitor (LY294002), or a Src inhibitor (PP2) for 3 h prior to harvest. FLAG-HDAC1 band intensities were quantified, as shown below each lane.