Potential mechanisms of differentiation inhibition by Lys298Glu C/EBPα. (A) DNA content of propidium iodide–stained nuclei of 32Dcl3 cells retrovirally transduced with either p42 C/EBPα, Lys298Glu, BRM-2, or MigR1 alone, selected for GFP positivity (day 0) and incubated in G-CSF (day 3). The apoptotic population is calculated as the percentage of cells with a sub-G1 DNA content. (B) Western blots show heterodimer formation of p42 and Lys298Glu C/EBPα in 293T cells transiently transfected with either HA-tagged p42 C/EBPα, Flag-tagged Lys298Glu, or together as indicated. Lane 1 of upper and lower panel is indicative of C/EBPα and Lys298Glu heterodimers. (C) Western blots show association of E2F-1 with p42 C/EBPα and the Lys298Glu and BRM-2 mutant in 293T cells transiently transfected with HA-tagged p42 or Lys298Glu or BRM-2 C/EBPα with E2F-1 individually or together as indicated.