FIGURE 6.

RUNX1 cdk phosphorylation increases induction of murine marrow progenitor proliferation in vitro. A, murine marrow cells isolated from mice exposed to 5-fluorouracil were transduced with pBABEpuro vector (Puro), or the same vector expressing RUNX1-ER (WT), RUNX1(tripleA)-ER, or RUNX1(tripleD)-ER, followed by puromycin selection, isolation of viable cells, and lineage depletion. Total protein samples from lineage-depleted marrow cells transduced with wild-type RUNX1 (WT), the tripleA variant, or the tripleD variant were subjected to Western blotting use ER antiserum and β-actin antibody. Expression of RUNX1 or its variants relative to actin was quantified as indicated below the panels. B, lineage-negative (lin-neg) murine bone marrow (mBM) cells were then cultured with or without 4-HT in medium containing FBS and IL-3, IL-6, and stem cell factor. Viable cell numbers in 4HT on days 0–10 after lineage depletion are shown from a representative experiment. C, ratio of viable cell counts on day 10 (with 4HT divided by without 4HT) is shown (mean ± S.E. of three determinations).