FIG. 5.

Hoxa9-immortalized progenitors exhibit a promyelocytic gene expression profile and upregulate expression of terminal differentiation genes in response to G-CSF and M-CSF. (A) Northern blot analysis of genes expressed in promyelocytes immortalized by wild-type Hoxa9 (clone HF1; lanes 5, 7, and 9) or by Hoxa9-WF (clone 1; lanes 6, 8, and 10) compared with gene expression in GM-CSF-responsive progenitors undergoing terminal differentiation to neutrophils and macrophages in the presence of GM-CSF (lanes 1 to 3) and with those expressed in NIH 3T3 fibroblasts (lane 4). By comparison to lane 1, lanes 2 and 3 contain RNA from the same cells cultured for an additional 24 and 48 h, respectively, in medium plus GM-CSF. The identity of each probe is designated at the left, and the origin of the RNA samples is identified above each lane. (B) Transcriptional responses to G-CSF is the same in cells immortalized by wild-type Hoxa9, Hoxa9-Atet, or Hoxa9-Gtet. The identity of the RNA sample is indicated above each lane, and the identity of the transcript is given to the left of each panel. rec, receptor.