Conditional activation of CEBPB in vivo prolongs survival of leukemic mice. (A) Methylcellulose colonies from peripheral-blood cells (5 × 10²) of untreated and 4-HT–treated C3H/Hej mice injected with 32D-BCR/ABL MigRI GFP ΔuORF C/EBPβ-ER^TAM cells; values indicate mean (plus SD) colony number from cells of 3 different mice for each group. (B) May-Grünwald-Giemsa staining of white blood cells from untreated (top panel) and 4-HT–treated (bottom panel) C3H/Hej mice injected with 32D-BCR/ABL MigRI ΔuORF GFP C/EBPβ-ER^TAM cells. (C) Survival of untreated (▴) and 4-HT–treated (•) C3H/Hej mice injected with 32D-BCR/ABL MigRI GFP ΔuORF C/EBPβ-ER^TAM cells. The y-axis represents survival percentage of untreated and treated mice; x-axis values indicate time of survival after injection (days).