Induction of differentiation in STI571-treated 32D-BCR/ABL cells is dependent on C/EBP activity. Gr-1 expression at 48 hours (A) and C/EBPα and G-CSFR levels at the indicated times (B) in STI571-treated 32D-BCR/ABL cells upon activation of Kα-ER^TAM, a C/EBP transcription repressor. Levels of Kα-ER^TAM were detected with anti-C/EBPα (14AA) raised against the C-terminus; endogenous C/EBPα was detected with anti-C/EBPα15C8 raised against amino acids 1 to 14 of mouse C/EBPα. GRB2 levels were measured as control of equal loading.