Fig. 5. Stabilization of RUNX1 by heterodimerization with PEBP2β. (A) Transient expression of RUNX1 (lanes 1–5) without (lane 1) or with increasing amounts (lanes 2–4) of PEBP2β. Lane 5 represents the cells treated with MG132. Whole-cell extracts of P19 cells were analyzed using anti-αB1, anti-β2 and anti-luc (an internal control). (B) Effects of exogenously expressed PEBP2β2 and proteasome inhibitor MG132 on the stability of endogenous RUNX1 in 32D cl3 cells. Whole-cell extracts were analyzed by using anti-αB1 and anti-β2. (C) Stabilization of RUNX2 and RUNX3 by PEBP2β. RUNX2 or RUNX3 with or without PEBP2β2 (shown as β2) was exogenously expressed in P19 cells and whole-cell extracts were analyzed by anti-Runt domain, anti-RD(10B7G8) and anti-β2.