FIGURE 4.

Overexpression of Ppm1b stabilizes EKLF. For a–c, transfected material is as indicated at the top, and the antibody used for probe is on the left. β-Tubulin was used as a loading control. a, co-expression of Ppm1b increases the levels of exogenous EKLF in 293T cells. Lanes 1 and 2, 3 and 4, and 5–7 are derived from biological replicates of transfections. b, Ppm1b also increases exogenous EKLF levels in K562 cells (compare lanes 2 and 4). c, deletion of the PEST1 sequence that is important for the physical interaction of EKLF and Ppm1b does not abrogate this functional effect. Lanes 1 and 2, 3 and 4, and 5 and 6 are biological replicates of transfections. d, stability of protein expressed from the indicated constructs (as indicated below) after transfection into COS7 cells was monitored after cycloheximide treatment as indicated. Left panel shows the data with full-length EKLF and right panel shows the data from the EKLF ΔZnF variant. Ppm1b decreases the turnover of full-length EKLF (p < 0.05) but has no effect on the stability of EKLF ΔZnF. The data presented here are representative of three independent experiments. Error bars represent the mean ± S.E. NS, not significant.